AP PSYCHOLOGY

Detailed explanation-1: -Having identical twins is not genetic. On the other hand, fraternal twins can run in families. Genetics can definitely play a role in having fraternal twins. For example, a woman that has a sibling that is a fraternal twin is 2.5 times more likely to have twins than average!

Detailed explanation-2: -Identical twins (also called monozygotic twins) result from the fertilization of a single egg by a single sperm, with the fertilized egg then splitting into two. Identical twins share the same genomes and are always of the same sex.

Detailed explanation-3: -Identical twins (left) share all their genes and their home environment. Fraternal twins (right) also share their home environment, but only half of their genes. So a greater similarity between identical twins for a particular trait compared to fraternal twins provides evidence that genetic factors play a role.

Detailed explanation-4: -Research published on January 7 in the journal Nature Genetics shows that identical twins differ by an average of 5.2 genetic mutations. The authors argue that these small differences between twins’ genetic code could change how scientists study human development.