Webbed feet. This webbing (syndactyly) between a baby's toes is due to Apert's syndrome, an inherited disease. Apert's syndrome, also know as acrocephalosyndactyly, also causes webbing on the hands and the premature closing of the skull bones resulting in a peak-shaped head. The webbing of the hands and feet is characteristic of Apert's, compared to other types of webbing the bones also become fused. Apert's syndrome is caused by a gene mutation and affects 1 in 160,000 births.