Does Polydactyly Affect Everyone the Same Way?

If polydactyly is caused by just a single gene that only affects the number of fingers or toes and nothing else, then it is typically a dominant trait. If you have one “polydactyly” copy of any of these genes you get extra fingers even when the other copy says to make five fingers.

How is polydactyly dominant?

Polydactyly. Polydactyly is an inherited condition in which a person has extra fingers or toes. It is caused by a dominant allele of a gene. This means it can be passed on by just one allele from one parent if they have the disorder.

Why are some dominant traits such as polydactyly not common?

Whether an allele is common or rare in a population does not depend on whether the allele is dominant or recessive. Dominance occurs when one allele masks the phenotype of another allele. In the case of polydactyly, an allele can become rare when the resulting phenotype is not an advantage for the organism.