I am a psychology major and I work with indivduals with mental illnesses. I have a client who has anti-social PD.
The thing is, and research shows, that both contribute to the illness. In some cases the indivdual grew up in a household that was very loving and "normal" ( I hate that word...). In other cases there has been research showing that some people who have the illness were abused of some sort during their childhood.
A child with antisocial is usually diagnoised before hand with ODD or conduct DO. Both of these disorders are "childhood DO's" and if they continue into adulthood they are comorbid with antisocial.
Genetics can play a factor as well because with any mental illness it can be passed down. The greater risk the child will have an illness is if a parent has one as well.
Antisocial PD is very difficult to treat because these indivduals do not have emotions. They are lacking emotions or the ability to feel.