John, when trying to distinguish between genetic and environmental components of behavioural traits, things get quite tricky. The only way you can really distinguish between the two is to find some young children of psychopaths who have also inherited the putative ‘genetic elements’, then bring one or more of them up in the house of empaths lacking such genes.
Empathy in my experience on an emotional level emerges as a result of experiencing it from others. I experienced none of it in my family growing up but experienced plenty of it on a gap year in Austria from a superb music teacher. Empathy became a part of my armoury as a result. But if you had evaluated me aged 17 you could have postulated, in the days before modern genetics allowed whole genome screening to take place, that I had inherited a ‘lack of empathy’ genetic tag from my parents. Aged 18, your conclusion would have been totally different. That should at least tell you that lack of exposure to empathy may lead to an undeveloped empathy function in the brain, which is different from saying that such a function is totally absent.
I can well imagine that if Baraitser grew up in Apartheid South Africa that it was eminently possible to have had an empathy-free childhood. Whether she inherited it from her parents, I do not know. But having parents not displaying empathy may well have been more common back then: it certainly was in the UK with all that ‘stiff upper lip’ exhortations….