*Some* aspects of gender is socially constructed, but others are apparently innate. There have been cases where boys were raised from very young ages as girls due to botched circumcision operations or disease operations in which their penis was lost and then removed. These kids weren't told they had once been boys. They were socialized as girls, raised as girls and yet they knew something was up. Many of the cases report eventual realization of the issue by the subject, a refusal to conform to the social construct given to them when there was no apparent reason to reject it - except that gender was innate in their biology and the role they had been forced to adopt was not compatible with it. Their biology knew they were boys, and it manifested itself no matter what.
That's why I believe gender, and even gender roles, aren't just social construct. The reason they became social construct in the first place is because there's a grain of biological truth in them. There is a biological reason why men tend to be more competitive and women more responsive to emotion and social for example, and why that has led to the social construct of "strong" men and "social" women. It doesn't apply to everybody, but on average yeah, you can see across the board that men dominate competitive careers and are less able to articulate their emotions on the whole. The social constructs and roles grew out of some basic natural tendencies of the sexes, but are of course massive generalizations and always will be. Social constructs are just ideas people have built upon until they become something people organize their lives around. But we know when it comes to the sexes there's reasons that, say, men protect women, and women protect children - real, logical and biological reasons. And ->-bleeped-<- proves, with little doubt, that there's something inside of people that prevents them adopting a social construct easily if their internal gender 'instinct' doesn't match the construct. I use the word instinct because for most of us, we don't even need ideas or words to feel there's a problem. There's some very real obstruction within that makes gender far more important than an external idea or lifestyle.
And then there's people like me who can ignore the roles and the constructs for the most part which should make me happier, if gender is just some idea made up by society. I should be able to ignore it, if so. But I can't because my own body rejects itself, regardless of what people say or think or what role I'm in. It literally has rejected itself biologically and chosen not to reproduce because of the condition it's in. It has a sickness, a debilitating condition that is curtailing its life - maybe not as visibly as a major physical ailment, but it has done its work all the same. I definitely think there's a lot more to it than just being a social construct.