Obviously some behaviors are inborn and aid in our survival as a species and some behaviors are learned. Example of an inborn instinctual behavior is the sucking reflex any mammal knows without being taught and aids in their early survival. Fetuses have been seen sucking their thumb in the womb. Other behaviors are learned. However, our genes are the result of natural selection on responses to situations in the environments of our ancestors. Our genes determine to some extent our intelligence, ability to learn and to carry out responses. There have been studies about personality traits in families and identical twins(even those reared in separate households) show a higher heritability for those traits, then fraternal twins, siblings or for adoptive siblings. Obviously in this case, the environmental role is not as great as the genetic. However, there is also a strong environmental component to other behaviors. Children learn by imitating their parents, peers, etc. There is also free will to behave in a certain way. Therefore, although our genetics affects our behavior, the environment too has a large role in behavior as well. This is why the nature-nurture controversy continues.