Thanks for the great question!
Our genes, which are made of DNA, determine what
traits we have, like the color of our hair. A
scientist named Mendel discovered that for
certain traits there are two different versions of
the underlying gene, called alleles. You get one
allele your mom and one from your dad. When mom
and dad give you the same allele, it will be
visible, but when they give you different alleles,
one tends to win out and is visible – we call this
the dominant allele, and the other
invisible allele is recessive. I’ve included a
picture called a Punnett Square that illustrates
In this picture, each parent has both a
dominant (uppercase) and recessive
(lowercase) allele of the B gene. If they were
to have four kids, then three of four would have
an uppercase B, the dominant allele, and this
trait would be expressed. One child, however,
would have two lowercase b’s, and this child would
exhibit the recessive trait.
Dimples are a human trait that are highly
heritable, that is, if your parents had them,
that means you likely have them. Dimples are the
dominant trait, meaning if one parent has them and
the other do not, it’s likely their child will
have them. So, people have dimples if one of their
parents has them. However, as you see in the
Punnett Square, it’s possible for two parents with
dimples to have a child without dimples, 25% of
the time. The science of genetics explains why
people have the traits we have.
Thanks again for the great question.
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