Why are twin-adoption studies powerful ways to untangle the effects of genes and the environment on thought and behavior? a. They allow both genetic and environmental similarity to be compared and...

Why are twin-adoption studies powerful ways to untangle the effects of genes and the environment on thought and behavior?

a. They allow both genetic and environmental similarity to be compared and contrasted. b. Twins share genes.

c. They allow for understanding epigenetic influences.

d. They allow researchers to experimentally manipulate genetic and environmental similarity.