Sophia and Olivia Are 12-Year-Old Identical Twins

Multiple Choice

Sophia and Olivia are 12-year-old identical twins. They have not yet experienced their menarche. They have both developed some secondary sex characteristics about the same time. Their mother had her menarche at age 13. The girls expect to experience their menarche at about the same time as each other due to their ______.

A) 50% shared DNA
B) contextual factors
C) 100% shared DNA
D) melatonin release