Oopsminty, I saw that programme with the toys and monkeys too. I didn't conclude that there are many inborn male/female differences, though.
I thought that young monkeys would surely have keenly observed the culture and roles of their elders. They had already learned the male and female modes of behaviour.
Similarly, boys and girls watch the adults around them, people in general and on films, TV etc. From babyhood to pre-school age, what do they tend to see? A lot of male doctors, female nurses, women looking after children, male action heroes etc.
Having two sons and two daughters I soon noticed the different way other adults approached, treated and influenced them. ('Oh, she's so beautiful', 'He's a real bruiser'.)
We reinforce our culture in the young without even being aware of it. Even the two year old boys at playgroup soon made guns out of Duplo, the girls played mum in the playhouse.
Not genetic, inbuilt differences - but our unthinking conditioning of them.