A Genetic problem: 12 fingers

[KMCB1234]

Just to ask professional researchers a question,
Normally, human beings are born to have ten fingers, but I noticed long ago some friends of mine in my hometown have twelve whereas their parents are normally with ten only. This I assume is a genetic problem which the bad gene (6 fingers on one hand) from a parent gets combined with another from the other parent. So how can we conclude such a case is not a harmless mutation ? Even though with twelve fingers, still they can lead normal lives anyway. I think it is a harmless mutation if that poeple can call mutation instead of genetic inheritance.

Thamnk you

[Monique]

The condition of having extra digits is called polydactyly. I am not sure what you mean with your last comment, you mean a spontaneous mutation vs an inherited mutation? Or a single mutation vs genetic disease?

Familial polydactyly occurs as a dominantly inherited trait, meaning that one of the parents will also have extra digits, in most cases this does not indicate a genetic disease: you only have an extra finger.

There are cases were polydactyly is associated with other genetic disorders or syndroms, where other symptoms or abnormalities are present.