What Type of Evidence Suggests the Genetic Basis of Traits

Multiple Choice

What type of evidence suggests the genetic basis of traits like cleft lip?

A) Concordance for monozygotic twins is much greater than for dizygotic twins.
B) Environment significantly affects such traits.
C) Genes predispose individuals to express the trait.
D) Risk increases as genetic relationships become more distant.
E) Some kind of threshold must be reached before trait can be expressed.