... as were those that think biology predetermines everything

Perhaps it was a reference to nature vs. nurture, and how they can both play a part in outcomes.

That's what I read into it.

While nature vs nurture is fun to speculate on, when raised in criticism of another's work it is usually only speculation and otherwise unproductive. Also often ignored is that they are somewhat conflated insofar as people's nature creates environments that then (not independently) nurture.

I'm not sure this is fair. Nobody really knows to what extent psychopathy is inherited vs caused by upbringing. The problem isn't necessarily disbelief in biology, the problem is nobody actually knows the answer.

Challenging something that's universally challenged seems comprehensible to me.