Why does having a genetic basis not mean that a behavior develops without experience?

Having a genetic basis for a behavior does not mean it develops without experience because behavioral development is the result of a continuous and complex interaction between inherited genetic material and the environment in which those genes are expressed.12

While genes can influence behavior, the assumption that they specify a developmental outcome without any contribution from contextual factors fails to acknowledge the complexity of the developmental process. At every level—from the gene within its cellular structure to the mature organism in its physical and social surroundings—interaction is the rule.1

For example, even in behaviors that appear to be "instinctive," such as aggression, an animal's adult behavior is not merely the expression of blind instinct, nor is it solely the result of developmental experiences. Instead, it emerges from the interplay between genetic predispositions and environmental factors, such as hormonal exposure in the uterus, early handling, or social interactions. Evidence of a genetic basis, such as that provided by selective breeding, confirms that genes influence traits, but it remains silent on how those traits are realized during an individual's ontogeny.21