What does? I made a few claims.
What is the alternative position you're suggesting?
I think the effects of evolutionary biology need to be considered when looking at behavioral differences. Evolutionarily speaking, women invest much more energy into growing, giving birth to, and caring for children than men. This leads to innate differences in behavior separate from social forces you are describing.
The reason why women are more involved in childcare after giving birth/nursery years is purely societal factors. It's expected of them to behave in that way in more conservative places and it's strongly implied in other places.