From his own stories alone, he definitely had messed up relationship to sex from the get go. He's spoken about how he lost his virginity because his own dad hired prostitutes on a foreign holiday when he was a teenager - and his dad was also having sex with prostitutes
in the same room at the time. His dad took him to brothels and was also leaving pornography around for him to find when he was younger, iirc. He mentioned being aware of sex when he was like 6 trying to see a house guest naked, even setting up a prank for his mum when he was like 8 where he sprayed foam cleaner and told her his
pen had 'got hard' and that came out - how does an 8 year old know enough about sex for that?
Purely my opinion, but even when Russell tries to laugh it off as a funny story, his dad always comes across as a wrong'un because almost all the stories involve examples of 'covert incest'/grooming or his dad being generally neglectful of him. No surprise that his dad was immediately loudly supporting him after the allegations came out, given he was basically the blueprint.
But having a terrible or messed-up childhood doesn't allow you to commit sexual offences yourself. Even if you can trace why he became a sociopath, it doesn't excuse his actions either