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Question: Does a cleft chin have to be inherited from one of the parents!?
my good friend has a kid who has a cleft chin!. she doesn't have a cleft chin, and neither does the father!. she said no one in her or the dads family has a cleft chin!. they did a paternity test so they know its his kid!. how is this possible!?Www@QuestionHome@Com

Best Answer - Chosen by Asker:
The cleft chin of your friend's child is an excellent example of "variable penetrance"--a gene that doesn't show up in your friend's facial features or in those of the child's dad, but it does show up in the child!.

If a child has a cleft chin, he or she has either
---two dominant alleles determining this trait
---or one dominant and one recessive allele!.

Possessing a cleft chin depends upon having the dominant gene itself as well as having a modifier gene!. In other words, if the modifier gene allows a child to inherit a cleft chin, then he/she still needs to have a working copy of the cleft chin gene!.

Genetics is complicated since traits can skip generations!.Www@QuestionHome@Com

Genetics is a funny thing, Because the Cleft Chin is a recessive trait, It could have been dormant in both families for generations, just because they say no one in their family has a Cleft chin doesn't mean someone in their distant family doesn't have it without them knowing!. Their child having one in these circumstances is highly unlikely but entirely possibleWww@QuestionHome@Com

well cleft chin comes from the genes
it could have been recessive in both parents, meaning it wasn't shown
but if the two recessive genes combined then thats why their child has a cleft chin
and a gene can be recessive for many generations until it is shown
so no need to freak outWww@QuestionHome@Com