Doug:
> What kind of bogus distinction is that? Aggressive
> dispositions can arise in large part from early social
> interactions, and are either reinforced or discouraged by
> later social interactions? What's a family but a social interaction?
There is quite a bit of literature suggesting that it is the current interaction that trumps learned patterns (e.g. conditioning by past interactions) under proper conditions. The whole purpose of the Stanford Prison Experiment http://www.prisonexp.org/ was to demonstrate just that point - that you can come from the impeccable family background (all participants were carefully screened) and still engage in thuggery if properly enticed. Check also Jack Katz _ Seduction of Crime_ who is quite persuasive.
Of course that does not mean that family influence and past behavior does not matter - it certainly does, but it is not always a decisive factor.
Wojtek