We have two boys and a girl (all now teenagers). My daughter was never into dolls and never really liked pink. She was into arts and crafts and loves knitting and sowing. The boys were completely stereotypical (plastic and wooden swords, guns, cars, diggers and tractors, soldiers etc).
We have good feminist friends (with three boys) who banned violent toys for boys. They always gave us the cat's bum face when they visited ours because their boys used to absolutely love playing with my sons' swords and shields. When we went out it for a walk, every stick they found was a gun - despite their parents vocal disapproval.
My friend's boys (now all strapping teenage lads) joke about how their parents banned them from having the toys they always wanted.
We definitely saw differences in toy preferences very early on. My daughter had zero interest in wheeled toys (despite my efforts) but both boys were fascinated by them virtually from day one.
I know my experience is not scientific. But there were some studies several years ago using baby apes (who obviously had not been conditioned by human systems or been exposed to advertising etc). Baby male apes showed a clear preference for mechanical toys over plush toys.
www.newscientist.com/article/dn13596-male-monkeys-prefer-boys-toys/
I'd love to hear others views on this topic... social conditioning versus biological predispositions.