There are some demonstrable biological differences between men and women. Men, on average, are taller, and there is a difference in distribution of mass (women aren't as top-heavy). There is some, albeit somewhat controversial, scientific evidence that men and women think differently (men better at math, women more right-brained, etc.). It is plausible that thousands and thousands of years of doing certain tasks resulted in our brains being evolutionary hard-wired a certain way depending on our sex, which justifies some differences, though those are largely superficial (even if men are on average better at math, that does not in any way suggest any given woman could not outperform most men in that area).

That being said, I'm not aware of any evidence against the basic premise that the vast majority of "gender roles" are entirely social constructs. Women liking the color pink, cooking, jewelry, taking care of kids, etc. -- that's all manufactured crap (most of it rather sickening).