Some people put their left thumb over their right when joining hands, while others do the opposite. The way people position their thumbs when joining hands is not determined by a single genetic trait. How people position their thumbs provides a clear example that the dominant trait is not always the most common one.

1. Joel Jara Cano

3. When people join their hands, some of them
put their left thumb over the right one, while
the other ones do it the other way around.
It is not a single genetic trait. It is the
clearest sample that shows that dominant is
not always common.

4. Father´s
side
autosomal
dominant
heredity
ME
Mother´s
side