20. Individuals with more than 5 fingers on each hand have a disorder
called "polydactyly." Shaded individuals on this pedigree have polydactyly.
Which is true?
Polydactyly is autosomal recessive
Polydactyly is autosomal dominant
O Polydactyly is sex-linked recessive
Polydactyly is caused by an extra chromosome