system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why is it that all humans have ten fingers and ten toes (and other common features) yet genetics allows random mutations for skin color hair color , height, weight, etc? why don't we see random three arms on some people, twelve toes, or three ears ?
gpt
Better answer, biology allows (and encourages) variation, above mutation. If your parents have different shades of skin, you are likely to inherent a shade similar, but different than either of them. If your parents have the same hair color, you are likely to as well, but if they have different color or shade, you are likely to inherit a shade with a slight variation from either of them. This isn't a mutation, it's a variation. If your parents come from populations of people that have different number of fingers from one another, you could inherit the traits of one, the other, or a variation of both. As it stands, your parents (absent a genetic, inheritable mutation) have the same number of fingers, so that's the number of fingers you are likely to inherit.