Complexities of Genetics and Behavior

In the context of behavioral genetics, the study of twin and adoption studies has significantly advanced our understanding of the genetic basis for various behaviors. Researchers have found substantial evidence for the heritability of traits; however, the interplay between genetics and environment complicates this understanding. Consider the following statements regarding genetic influences on behavior:

1. Genetic predispositions are solely responsible for behavioral traits.

2. Environment can amplify or suppress genetic influences on behavior.

3. Twin studies often show that identical twins are more similar in behavioral traits than fraternal twins, suggesting a genetic component.

4. The interaction between genes and environment can lead to different outcomes in behavior despite similar genetic backgrounds.

Which of the above statements is true regarding the relationship between genetics and behavior?