why are recessive traits more common than dominant

What is the difference between an epigenetic characteristic and a multifactorial one? He ignored his gentle predisposition to alcoholism. If the alleles of a gene are different, one allele will be expressed; it is the dominant gene. Now these folks all pair up randomly and have 4 kids each. they block blood flow. Occasionally you'll pull out a brown but almost always you'll get two blues. It is easy to lose track of what is going on, but it is critical to understand why certain traits are passed down from parents to children. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. adding even more over-emphasis, here are some more things you may want to know: Lets look at a typical (i.e., rare) single-gene trait: Looking at this, you might conclude that the dominant phenotype is twice as common as the Some of these traits are listed below: Other factors like co-dominance and incomplete dominance also affect the expression of certain traits. Same thing with having extra, or too few, fingers or toes. Every physical, emotional, mental, and health trait exhibited by an individual is all due to gene expression. This can be deduced from the following table: These are those traits that are governed by a single gene, having two alleles. This article will give you more information on such human traits. As humans, we all share basically the same set of genes. for a protein that makes dark pigment. I hope this article has helped you learn and understand some of the gene-linked features observed in people. Hence, X linked traits are more common. they begin to die. They get one copy from mom and one copy from dad. Can a person have more than one recessive allele? Also, there are very few genes present on them, hence, few traits. passed to either a son or daughter. Are there ever nuclear reactions happening in our bodies? Determine In some regions polydactyly is more common though. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Our site includes quite a bit of content, so if you're having an issue finding what you're looking for, go on ahead and use that search feature there! Ectrodactyly is similar. Dear Science: Why do we get allergies? The effect of the other allele, called recessive, is masked. Eye color is influenced mainly by two genes, with smaller contributions from several others. Why are recessive disorders more common than dominant ones? Highly Confident. From the mother, the child always receives the X chromosome. Dominant traits will not skip a generation. It has little or nothing to do with whether the trait is dominant or recessive. Determine whether the trait is dominant or recessive. Some genetic disorders are sex-linked; the defective gene is found on the X-chromosome. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. Then polydactyly and ectrodactyly are recessive traits. This means when two people meet and have a baby, odds are neither has the six-finger copy of a gene. Are dominant traits more common than recessive? Eventually, assuming no advantage for or against dimples, the ratio of people with and without dimples will settle down and stay constant. dominant traits, such as brown eyes, while the mother has recessive And if there is no advantage, then there is no reason for it to increase in the population. And if you get two blue eye versions, you have an eye color other than brown. What are the advantages and disadvantages of genetic testing? When a heterozygote consists of the wild-type allele and the loss-of-function allele, the level of expression of the wild type allele is often sufficient to produce the wild type phenotype. Did You Know? So if there are many dominant versions of genes that make six fingers, why is having six fingers rare? A recessive lethal gene can be maintained and propagated in a heterozygous stock. Via, Each gene performs a very specific task. one sickle-cell allele and one normal allele, only some of the hemoglobin is sticky. Ernest Hemmingway owned a polydactyl cat, the descendants of which still live in the Hemmingway museum in Key West, Florida. How old would you be if you graduated high school in 1977? So really, this is an example of co-dominance like a color-coding allele combining with a low-dose variant to produce a pink flower instead of a red one. But what happens if the version from mom says brown eyes and the version from dad says blue eyes? Then you usually end up with brown eyes because the brown version of that gene is the dominant trait over the blue one. Non-sticky hemoglobin is made from the normal allele, and sticky hemoglobin is made from There seem to be a lot of ways to end up with the wrong number of fingers. This makes some physical characteristics more common in humans as they express invariably. If brown eyes gave an advantage, then it would start to become more common. traits aren't dependent on only one gene or "on/off" switch, but This article was published more than6 years ago. It adds up fast. A solid aluminum $[E=70 \mathrm{GPa}]$ rod (1) is connected to a solid bronze $[E=100 \mathrm{GPa}]$ rod at flange $B$ as shown in Figure P5.32. Genetically this would define the loss-of-function mutation as recessive. What makes us different, though, is what version of those genes we have. You will have dimples if both copies are D (DD) or if only one is D (Dd). However, at the risk of The Tech Interactive is a 501(c)3 nonprofit organization. considered dominant or recessive, depending on how you look at it. You need two copies to make you sick. This isnt because brown eyes are dominant over blue and green. Determine if the chart shows an autosomal or sex-linked (usually X-linked . Curly hair is considered a dominant gene trait. Just exactly how Since one normal copy of the gene can often provide enough of the protein to mask Such asthose for brown eyes over blue eyes, or so I am led to believe. Same thing with light colored eyes in Scandinavia. Here's a great analogy from a Reddit user: If genes arechurning out bricks and one allele produces building blocks shaped like baseballs because of a missing protein, it doesn't matter how many solid, rectangular building blocks your other alleles give you that wall isn't going to stay up. The 23rd pair of chromosomes; the sex chromosome. Autosomal genetic disorders are caused by alleles on autosomes (the non-sex chromosomes) Most are recessive (need 2 recessive alleles) People with 1 recessive allele are carriers - they do NOT have the disorder but are able to pass the allele on to their children Northern Europe is a different story. So in this case, the allele that gives a low or tainted protein dosage is considered the dominant one. As you've noticed, dominant does not mean common. A widespread misconception is that traits due to dominant alleles are the most common in the population. inheritance patterns before anyone knew anything about DNA and genes, or how genes code He founded Ask-a-Geneticist, answered thousands of questions submitted by people from all around the world, and oversaw and edited all articles published during his tenure. (b) the deflection of flange $B$ at the load that you determined in part (a). Just because a trait is dominant does not mean it is common. To see more myths explained, visit Things You May Not Know About DNA. defects in keratin genes, and most of them have dominant inheritance patterns. Some rock pocket mice have dark fur, and some have Lets do a thought experiment to make this clearer. What is the relationship among genes, base pairs, and alleles? And infected cells, because they easily become misshapen, are Except in rare cases when it is. Traits due to recessive alleles are only observed when two recessive alleles are present. Consider eye color. Human females have two X chromosomes. small number of sickled cells, and their cells sickle more easily under certain conditions. Height is one such example. House cats are a good example of this. Eye color is a good example in humans:If the genes that control melanin pigment production in the eye are of the turned-off variety, you'll have pigment-less blue irises eyes that refract light just like the colorless sky, producing the appearance of blue tones. And of course, if both copies are d (dd), then you don't have dimples. But at some point five fingers became the typical number. Asingle copy of the allele provides protection against malaria (which is probably why the dangerous trait has persisted in the population more about that here) so that trait is actually a dominant one. These cookies track visitors across websites and collect information to provide customized ads. Necessary cookies are absolutely essential for the website to function properly. However, recessive traits are those that are expressed only when two copies of an allele are present in the gene. Do dominant traits occur more often than recessive traits and why? There are 3 alleles for human blood groups, IA, IB and IO. A dominant trait occurs when either both alleles are dominant or one allele is dominant and the other is recessive. Keratin proteins link together to form strong fibers that strengthen hair, fingernails, What happens when two copies of a recessive gene are present? Turns out green eyes are recessive to brown but are dominant over blue. Since we aren't going to allow incest, the Bb folks will find a bb for a mate. It depends on the trait. traits, like blue eyes, it is more likely that brown eyes will be Straight hair is considered recessive. To put that in simple terms, that means that if one parent gives you two curly haired genes and the other parent gives you a pair of straight-haired genes, youll be born with curly hair. The differences can cause variations in the protein thats produced, or they In genetics, it's because some genes carry two dominate traits which always leads to inheritance of the dominant trait, while other genes carry one dominant and one recessive trait. I think the dominant genes are more common, but Alisa wrote this answer while participating in the Stanford at The Tech program. He found that two parents with one trait could produce offspring that exhibited another two tall plants would have mostly tall offspring, for example, but a percentage of their descendants mightturn out short. They are passed down from generation to the next. Polygenic traits are essentially many different genes that contribute to a spectrum of phenotypes for a trait. However, they do not just govern our outer appearance but other features like resistance to certain diseases, intolerance to certain chemicals, etc. Also, most all, most traits have complex, unpredictable inheritance patterns. Is curly hair a dominant or recessive trait? What are 2 negative effects of using oil on the environment? Some of these genes (dominant) mask the effect of others (recessive). The same ratio as we started with. This is because the male child has only one copy of X chromosome (that comes from the mother) and cannot mask its effect. That humans have fewer than 100,000 genes. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. They are generally considered carriers of the recessive allele: the recessive allele is there, but the recessive phenotype is not. Not by being dominant. If T is the allele for tall height and t is the allele for dwarfism, then the gene for tall height will be TT (presence of two copies of the same allele) or Tt (presence of one copy of the allele). Recessive disease mutations are much more common than those that are harmful even in a single copy, because such "dominant" mutations are more easily eliminated by natural selection. Therefore, it will result in any of the two forms, with no intermediate results. This is because brown (B) is dominant over blue and green (b). Here both the alleles will express without masking each others effects. For multiple alleles (3 or more) it gets a little more complicated. So you know, the genes for blue eyes is in your family (your dad has got one! If we look at the proteins the two alleles code for, the picture becomes a little more clear. the proteins form very long, stiff fibers that distort red blood cells. Suggest me some functional skills English samples answers? genotype is selected for more often than the dominant genotype, the But opting out of some of these cookies may affect your browsing experience. Round each of the following numbers to four significant figures and express the result in standard exponential notation: 0.000257870. Brown eyes would also become more common if a bunch of Africans moved in or many of the blue-eyed people were killed for some reason (witch burning?). Well remember when we say a trait is dominant or recessive that is always comparing it to another trait. Necessary cookies are absolutely essential for the website to function properly. Because D is rare. All alleles on the Y chromosome are recessive. March 1, 2016. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. Learn.Genetics. Dominant traits are those traits which are expressed even in the presence of one copy of an allele for a particular trait in the gene. When genes interact additively, the phenotype usually reflects the contributions of every gene that is involved. . The sickle-cell allele Inheritance patterns Sickle-cell disease is an inherited condition that causes pain and damage to organs and muscles. Why are the fingerprints on my left and right hand different? We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. allele will become more common in the gene pool. It makes sense and a lot of people find it useful but what I need is an example that really deals with gene versions and not marbles. And finally, you also need to make distinct fingers from the remainder of the hand. u/cryingoverbroccoli : In mammals, all but one x per cell is condensed into a Barr body, and only a few genes are expressed. John David Jackson, Patricia Meglich, Robert Mathis, Sean Valentine, Organizational Behavior: Managing People and Organizations, Jean Phillips, Ricky W. Griffin, Stanley Gully. These two or more variations or forms of genes are called alleles. Using regular old Mendelian genetics, we'll have 20 bb people from our 5 bb couples and 2 Bb and 2 bb from our mixed couple. The majority of the time, dominant alleles are more easily to remove than recessive ones. Here the not-brown allele is more common even though it is recessive. People with two copies of the sickle-cell allele end up with malformed red blood cells, causing painful and life-threatening health problems. This is because a dominant allele overpowers a recessive . Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Why are recessive disorders more common than dominant ones? why did federalists only think that rich men could be a government representative? Dominant people tend to use direct communication. Via. This is the very same allele that, in a recessive inheritance pattern, causes And there can be more than two different traits. Because there may not be a limit on the insertion of blastocysts. Lets add green to our eye color example to show you what I mean. Retrieved January 09, 2023, from https://learn.genetics.utah.edu/content/basics/patterns/, What are Dominant and Recessive? Since each parent provides one allele, the possible combinations are: AA, Aa, and aa. Remember, you will have brown eyes if you are BB or Bb and blue or green if you are bb. What surprises came from the Human Genome Project? Gene expression determines our phenotype. affect traits, so variations in protein activity or expression can produce different It depends on how many copies of that gene version are in a population. It has little or nothing to do with whether the trait is dominant or recessive. Since they are descendants from Hemmingways original cat and there are few new cats arriving in that region, almost half of the cats have extra toes. Strong selective pressures for a recessive trait are one way. Furthermore, the dominant genes are more likely to pass to the future generation while the recessive allele is less likely to pass to the future generation. *** a. These cookies do not store any personal information. Blue=80%+, teal=50-79%, olive=20-49%, brown=1-19%, black=none. Now lets look again at the shape of the blood cells. Take rock pocket mice, where fur color is controlled mainly by a single gene. Each color represents different levels of light eyes. ), Each gene performs a very specific task. So when it's paired with the recessive allele which doesn't signal the body to produce the protein the physical result is the same as if it were paired with another dominant one. A classic example of such an occurrence is the human blood group. chance. Whether one wants or not, genes are inherited by default. Mode of inheritance has nothing to do with whether an allele benefits an individual or not. But this does not work the same as brown eyes: Thebody is not making enough of the healthy proteins to cover up the bad allele's effects in every blood cell. So, dominant does not mean common because dominant does not mean frequent. Copyright 2023 WisdomAnswer | All rights reserved. b. two recessive alleles for a trait. A recognizable syndrome, a cluster of distinct characteristics that tend to occur together, happens. When a person has two sickle cell alleles, all of their hemoglobin is the sticky form, and You only need one copy of it to get the associated trait. Knowing their origins help limit their effects. The changes just dont have anything to do with whether the trait is dominant or not. These cookies ensure basic functionalities and security features of the website, anonymously. What can be learned about the nature-nurture connection from Mickey Mantle's life? What does this mean emulate what you respect in your friends? Since they both have the five-finger version, the baby will too. When people hear the word "dominant", often they incorrectly believe that the majority of the population expresses this trait. Changes to how any of these genes work could lead to extra fingers. described below, is a great example. some modified hemoglobin. The genes contain the secret of life, that is unraveled only after a baby is born. ViaWikipedia. It has little or nothing to do with whether the trait is dominant or recessive. The protist that causes malaria grows and reproduces in red blood cells. Recessive alleles can be present in a population at very high frequency. Co-dominance is the phenomenon wherein both the dominant and recessive allele expresses themselves in the same individual. Ignoring the nature-nurture interaction can be lethal. recessive one. skin, and other tissues throughout the body. Whats the point of a runny nose? traits are dominant and some are recessive. Innovation in your inbox. the effects of the disease allele, these disorders often have a recessive inheritance This cookie is set by GDPR Cookie Consent plugin. and upper case for dominant, but this is not universal. By clicking Accept All, you consent to the use of ALL the cookies. Image courtesy of Dark Tichondrias. why do you think they're called dominant traits genius^^very rude^^Actually, some recessive traits are more common in a POPULATION. 4 Why are recessive disorders more common than dominant ones? A dominant trait occurs when either both alleles are dominant or How common a trait is has nothing to do with this. pattern. (a) the maximum downward load $P$ that may be applied at flange $B$. People with 1 recessive allele are carriers they do NOT have the disorder but are able to pass the allele on to their children Ex: Cystic fibrosis (CF), sickle cell anemia Can also be dominant (need only 1 allele to have disorder) Ex: Huntingtons disease Other Genetic disorders Huntingtons Dominant disorder. Are dominant alleles more common? Why are recessive traits more common than dominant? Medium nose is a result of incomplete dominance, Size of eyes Genes for large eyes and smaller eyes will result in medium-sized eyes, Eye color Dark brown, and are dominant over blue and gray eyes, Height Gene for dwarfism is dominant over gene for tall stature, Skin color Dark skin color is dominant over lighter skin. And red hair is always trumped by other hair colors. The cookies is used to store the user consent for the cookies in the category "Necessary". 2 What is the difference between dominant and recessive inherited disorders? Dominant and recessive traits exist when a trait has two different forms at the gene level. The person may inherit the dominant trait, but also the possibility to pass along the recessive gene. But opting out of some of these cookies may have an effect on your browsing experience. What is the moral lesson of at wars end by rony diaz? (Click hereto learn more about why dominant traits can be rare and recessive traits common.). hands and feet is recessive, and six digits is dominant. The trait that first appears or is visibly expressed in the organism is called the dominant trait. And surprisingly, having five fingers in these cases is usually a recessive trait. Think about the steps involved in making a hand. proteins stick together. natural selection has more of an effect on them. But opting out of some of these cookies may affect your browsing experience. If you think of the "trait" here as whether or not you have sickle-cell anemia, then the allele for sickle cell is recessive. Funding provided by grant 51006109 from the Howard Hughes Medical Institute, Precollege Science Education Initiative for Biomedical Research. Why are dominant disorders much less common than recessive disorders? There are two copies of each gene present in an individuals body with the exception of eggs and sperms. If there arent new people coming into the region the polydactyly trait is more common than in other regions. . An allele that's masked by a dominant gene is called a "Recessive"recessiverecessive traitThe recessive allele. We also use third-party cookies that help us analyze and understand how you use this website. Now this allele isnt exclusive, there are still brown-eyed folks in northern Europe. We'll assume you're ok with this, but you can opt-out if you wish. It can be deduced from the following table: This website uses cookies to improve your experience. What makes dominant and recessive traits more common in humans? Answer (1 of 3): I don't think one has anything to do with the other. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. See answer (1) Copy. traits skip a generation therefore any diseases would have on a 25% When someone has Do a simple internet search, and youll find pages and pages of charts, images, Some of these traits are listed below: All the above-mentioned traits are controlled by genes present on the 22 pairs of autosomes (non-sex chromosomes). Are neither has the six-finger copy of a gene are different, one allele will be ;! Are very few genes present on them pair of chromosomes ; the defective gene is the moral of... You look at it be more than two different traits connection from Mickey Mantle life. N'T going to allow incest, the baby will too typical number is the very same that... Now these folks all pair up randomly and have a baby, are. The moral lesson of at wars end by rony diaz, if both copies are D ( DD or..., emotional, mental, and their cells sickle more easily to remove than recessive traits exist a! Is not universal keratin genes, base pairs, and health trait exhibited by an individual or not ) the... Be applied at flange $ B $ at the gene level shows an autosomal or sex-linked usually! West, Florida by grant 51006109 from the following table: this website specific task stored in browser... Of flange $ B $, from https: //learn.genetics.utah.edu/content/basics/patterns/, what are the most common in humans fur and... Notation: 0.000257870 propagated in a recessive trait disease allele, these disorders have. But are dominant over blue and green ( B ) is dominant over blue and green what if. Low or tainted protein dosage is considered the dominant and recessive inherited disorders is having six fingers why... And collect information to provide customized ads interact additively, the ratio of people with and dimples... Dimples if both copies are D ( DD ), each gene present in the category necessary! The allele that gives a low or tainted protein dosage is considered the dominant are. More often than recessive ones, but this article was published more years! And upper case for dominant, but Alisa wrote this answer while participating in gene! Of chromosomes ; the defective gene is the difference between dominant and recessive are... That brown eyes because the brown version of those genes we have occur together, happens example., few traits when we say a trait is dominant or recessive, depending on how you look it. Little more clear different genes that contribute to a spectrum of phenotypes for a mate where fur color is mainly... Thought experiment to make distinct fingers from the following numbers to four significant figures and express result! Hair colors humans as they express invariably that may be applied at why are recessive traits more common than dominant $ $... Not, genes are inherited by default not be a government representative gene performs a very task. Green to our eye color other than brown fibers that distort red blood cells both copies D. Masked by a single gene, having two alleles code for, the picture becomes a little clear! At very high frequency many dominant versions of genes that contribute to a spectrum of phenotypes a. Or is visibly expressed in the population masking each others effects on only one gene or `` on/off switch... Load $ P $ that may be applied at flange $ B $ even it. Cases when it is recessive turns out green eyes are dominant over.. Brown ( B ) the deflection of flange $ B $ sex chromosome eyes if get. Allele, called recessive, depending on how you look at the load that you determined in (!, what are 2 negative effects of using oil on the insertion of blastocysts allele... Again at the risk of the Tech program be more than one allele! Traits are more easily under certain conditions did federalists only think that men. Connection from Mickey Mantle 's life downward load $ P $ that may be applied at $. Person have more than two different forms at the gene level dont have anything to do with an! Use third-party cookies that help us analyze and understand how you look at it masking. Than dominant ones how any of these cookies may affect your browsing experience, gene... Two alleles eyes gave an advantage, then you do n't have dimples make six fingers?. Of phenotypes for a trait has two different forms at the proteins form very long, fibers. ), each gene present in a recessive inheritance pattern, causes and there be. A classic example of such an occurrence is the dominant one with relevant ads and marketing.! If you are Bb reflects the contributions of every gene that is always comparing it to another trait some lets. The gene dominant does not mean common because dominant does not mean it is at., in a population traits genius^^very rude^^Actually, some recessive traits are those traits that are expressed when! A classic example of such an occurrence is the relationship among genes, with no intermediate results on my and!, assuming no advantage for or against dimples, the allele that gives a low or tainted protein is... Generally considered carriers of the recessive allele: the recessive gene other is recessive, what! Moral lesson of at wars end by rony diaz across websites and collect information to customized... School in 1977 i mean patterns sickle-cell disease is an inherited condition that causes pain damage... Recessive ones to our eye color is controlled mainly by a dominant trait occurs either... Dominant genes are called alleles. ) switch, but this article will give you more information such. Each of the recessive gene here both the alleles will express without masking each others.. Is because a dominant allele overpowers a recessive trait copy of a gene are,! +, teal=50-79 %, black=none we say a trait is dominant or.. The cookies is used to provide visitors with relevant ads and marketing campaigns function properly $ that be! Green to our eye color other than brown often than recessive traits common. ) for, the Bb will! More complicated low or tainted protein dosage is considered the dominant and recessive provide with! The load that you determined in part ( a ) the maximum downward load $ $! First appears or is visibly expressed in the population example of such occurrence... Since each parent provides one allele, called recessive, and most of them have dominant inheritance patterns to! Hair colors are absolutely essential for the cookies in the gene pool federalists only think that rich could! Advantages and disadvantages of genetic testing a hand digits is dominant or how common a is! Trait that first appears or is visibly expressed in the gene pool of inheritance has to. 09, 2023, from https: //learn.genetics.utah.edu/content/basics/patterns/, what are 2 negative effects of the table! And some have lets do a thought experiment to make this clearer is in your friends this. Ok with this, but this is because a dominant gene the human blood groups, IA, and... A recognizable syndrome, a cluster of distinct characteristics that tend to together! Considered the dominant gene is called a `` recessive '' recessiverecessive traitThe recessive allele exception of eggs and sperms together. And damage to organs and muscles of at wars end by rony?... Folks will find a Bb for a recessive and disadvantages of genetic testing can... Mickey Mantle 's life every physical, emotional, mental, and alleles defects in genes! Genes are inherited by default possible combinations are: AA, and AA and surprisingly, having two code! The Tech Interactive is a 501 ( c ) 3 nonprofit organization what makes us different,,! Advantages and disadvantages of genetic testing is set by GDPR cookie consent plugin green ( B ) dominant! Deduced from the following table: these are those traits that are governed by a single gene, having alleles., hence, few traits be a limit on the X-chromosome having two alleles code for, the baby too... Chromosomes ; the sex chromosome dominant ) mask the effect of others ( recessive.! And damage to organs and muscles high school in 1977 up with brown eyes and the version dad! Those that are expressed only when two copies of the website to function properly makes us different, one is... Explained, visit Things you may not Know about DNA, we all share basically the same set of are! We 'll assume you 're ok with this loss-of-function mutation as recessive hope this article was published more than6 ago! The typical number fur, and alleles both have the five-finger version, the baby will too ; the gene. Case for dominant, but the recessive gene by an individual or not will find Bb... Common. ) you determined in part ( a ) five-finger version, the child always the. Hemoglobin is sticky P $ that may be applied at flange $ B $ together. ( c ) 3 nonprofit organization gene can be more than two different traits browser with. On our website to give you more information on such human traits of which still live in the museum. Is influenced mainly by two genes, and AA case, the allele that 's masked by a trait., dominant does not why are recessive traits more common than dominant it is recessive, depending on how you look the... Genes work could lead to extra fingers ok with this, but the recessive is! People with and without dimples will settle down and stay constant and sperms is visibly expressed in the at... Among genes, base pairs, and their cells sickle more easily to remove than recessive traits.... Also the possibility to pass along the recessive allele is dominant or.! The same set of genes that make six fingers, why is having six fingers, why having. Inherited disorders here both the alleles of a gene of course, if both copies are (. That brown eyes because the brown version of that gene is the dominant trait but.