The Twins Project

Nature and Nurture

How much of your interests, abilities, and difficulties are due to genes (“nature”), and how much are due to your environmental experiences (“nurture”)?

Even more importantly, how do your own genetic characteristics interact with your life experiences to shape your unique self?

Twins can help us answer these questions!

Identical twins (also called monozygotic, or MZ twins) are genetic duplicates: They share 100% of their genes.

Fraternal twins (dizygotic, or DZ twins) share the same amount of genes as two “regular” siblings: They share 50% of their genes.

All twins raised in the same family share a common environment, such as their parents and their schools. At the same time, twins also have important experiences that are different from one each other, such as friendships. Comparing how similar identical and fraternal twins are can tell us about the influence of genes on personality, talents, interests, school grades, mood and anxiety, behavior problems, and more.