1. Women are less capable than men at physical labour, that is a simple fact. Carpentry, plumbing, garbage disposal, the military and fields like mechanics are still dominated by men, just walk past a construction site for proof of this. It's not sexist, by the way to suggest that women as a gender can't lift as much as men can, you might as well call it sexist that I think men are usually taller than women.
2. I have never suggested that women are unfit for these jobs, only that women choose to work in different fields.
3. Now regarding daycare instructors being mostly women I think you're right to think a lot of this is due to cultural stigma but I also think that women by nature just enjoy children more. Call me sexist, call me old fashioned but this has been my experience in interacting with female friends, girlfriends, family members etc. Women like children more and women choose to spend more time with children. I also think men tend to place more of a value on money and childcare and education is a notoriously poorly paid field.
4. My point was simply to showcase something I believed pointed to an innate difference between men and women. Men are more aggressive and more likely to be violent, I believe this is evolutionary and inborn, you're free to believe that every single difference that manifests between men and women is the result of social conditioning. I will disagree with you.
http://en.m.wikipedia.org/wiki/Sex_d...man_psychology