Which of the Following Is NOT a Piece of Evidence

Which of the following is NOT a piece of evidence discussed in the text for the genetic influence of language disorder?

A) Specific genes on the 7th chromosome have been linked to language disorder.
B) The prevalence of language disorder increases more than five times for kids who have at least one family member with the disorder.
C) Siblings of those with language disorder, even when not diagnosed, often show subtle difficulties with phonemic awareness and grammar.
D) Heritability estimates range from 0.5 to 0.75.