Pedigree Practice

By Ms Baker
Photo by Here's Kate; The ability to tongue-roll is an inherited trait.

Photo by Here's Kate; The ability to tongue-roll is an inherited trait. Can you tongue-roll? Can your parents?

Go here to work on the problems. When you’re attempting to answer these problems you must first answer the following questions:

a) Is this a sex-linked trait or a non-sex linked trait?

b) Is this a dominant trait or a recessive trait?

  • phoenixia

    I tried to solve the problems and for problem 1, I deducted, based on what we learned about genes, the punnet square, and what I found out about sex related lung diseases, I deducted that the disease was not sex related and that the disease was a recessive trait. In answering the solution in problem 1, I believe that a=aa, b=Aa, c=Aa, and d=Aa.
    I also tried to solve problem 2, I believe the disease has a tendency to get caught by the females in the family because the majority of the people who have it were females. I determined that a=Bb, e=BB, and d=bb because in this problem the disease was a dominant trait.
    I also tried to solve problem 3 and I determined that the disease was a recessive trait and that F has a 50% chance that it would get the inherited disease.
    I also believe that in problem 3 , the disease was not sex related

  • Vasiliki

    This is a non-sex linked trait. If one of her parents has a dominant trait overpowering then the offspring has a chance of inheriting it, but the offspring is not a carrier.

  • Matt C

    This trait is a non-sex linked trait. This trait is a dominate one according to If one of your parents has the trait to roll your tongue its Rr and if both do then its RR. There both dominate. For example my dad can roll his tongue but my mom cant. In conclusion to this my sister can now roll her tongue while I cannot roll my tongue.

  • phoenixia

    This ability to roll the tongue may not be sex related but a study done with undergraduates of Ohio State proved that the differences between the sexes did exist. 77.4% of men could roll their tongues while only 69.7% of women could roll their tongues. Also a difference between left handed and right handed people showed differences in tongue rolling ability:about 62.8% left handed people could roll their tongue while 74.8% right handed people could roll their tongues.
    What causes this to happen if it is not a sex related disease? Could your dominant hand determine this trait too?

  • Guy

    I agree with Vasiliki and Matt C. This trait is 100% non sex linked. I cannot role my tongue, but my mom dad and younger brother can role their tongues. Although I know a friend who could tongue roll and both of his parents could roll their tongues. I found out through doing further research that it is possible for you to be able to roll your tongue even if both your parents cannot. I found this information at Also tongue rolling is a dominant trait and no tongue rolling is a recessive trait. Also human genetics are non sex link besides the ones that determine solely male and female traits.

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