My parents influenced me little, but what I read when I was 9-14 practically formed my identity. I know you said that he (or maybe this is another brother) was reading Camus, and Dostoyoevsky, but... what were YOU reading at that age?
Personally, I was reading Jack London. It's pretty easy to make the rectalinear connection to my currect materialism and Nietzschean uhh... sensibilities. Of course, London was also a mega-Bolshy, but I didn't pick up on that while I was reading his stuff.
I find that reading materials (ones CHOSEN, anyway) during early adolescence lead to more life-changing uhh... you know. Thingies.
WAX EYES. TRAINWRECK. TAKEOVER.