Multiple choice

A study of a disorder reveals that monozygotic twins are concordant 30-40% of the time, whereas full siblings are concordant 20% of the time. Which of the following is the best interpretation of this finding?

  1. The trait has no genetic component.

  2. The trait is completely determined by genetics.

  3. Genes contribute to the trait, but are not deterministic.

  4. The trait must be due to the biology of twinning.

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

There is an increased twin concordance, suggestive of a genetic contribution, but since twins are not fully concordant, other non-genetic factors must also be involved.