How does this quote, “if you can’t measure it, it doesn’t exist” tie into vulnerability?

Polydactyly is expressed when an individual has extra fingers and/or toes. assume that a man with six fingers on each hand and six toes on each foot marries a woman with a normal number of digits. having extra digits is caused by a dominant allele. the couple has a son with normal hands and feet, but the couple's second child has extra digits. what is the probability that their next child will have polydactyly? polydactyly is expressed when an individual has extra fingers and/or toes. assume that a man with six fingers on each hand and six toes on each foot marries a woman with a normal number of digits. having extra digits is caused by a dominant allele. the couple has a son with normal hands and feet, but the couple's second child has extra digits. what is the probability that their next child will have polydactyly? 1/8 1/32 3/4 7/16 1/2