This pedigree is of a rare trait, in which children have extra fingers and toes. Which one of the following patterns of inheritance is consistent with this pedigree

Options

A. Autosomal recessive
B. Autosomal dominant
C. Y-linkage
D. Sex linked recessive

Answer

C

Explanation

Y-linked disorders are caused by mutations on the Y- chromosome. Because males inherit a Y-chromosome from their fathers, every son of an affected father will be affected. Because females inherit an X-chromosome from their fathers, female offspring of affected fathers are never affected.