Sex based oppression can be rooted in biology, in that the physical differences between men and women are often exploited. Those differences are always there, but how we make use of those differences isn't necessarily hardwired
humans are ever rising above our biological urges and developing as a species and society. So it's not inevitable that we exploit those differences in negative ways
I do not for example believe it inevitable that men will rape women. I think the difference in rape across the world show that society/culture has a huge /dominant impact on rape
We may have a biological urge to go to the loo, but we retstrain ourselves until we find a clean loo.