Heredity and Traits

Identical twins Gerald Levey (left) and Mark Newman were separated at birth and raised in different cities. When they were reunited at age 31, they discovered some astounding similarities. Both were volunteer firefighters, had mustaches, and were unmarried. Both liked to hunt, watch old John Wayne movies, and eat Chinese food. They drank the same brand of beer, held the can with the little finger curled around it, and crushed the can when it was empty. It’s tempting to conclude that all of these similarities are due to heredity, but we should also consider other explanations: Some may result from shared environmental factors such as social class and upbringing, and some could be due merely to chance. For any given set of twins, it is difficult to know for sure.