Saying that sex is a construct is perfectly valid. It's not saying sexed genital & reproductive features of the body are constructed; it's not saying the body isn't real; it's to say that what those bodily features mean is constructed by society. The meanings are constructed.

Why should a penis & testicles on a new born baby mean anything about their role or potential, any more than we would call out their weight at birth & go, there it is, that's who they are forever now, let's label them as that & put it on all their paperwork into adult life.

As Radical Feminist theory explained decades ago, sexed features of the body are constructed to mean sex rank. That's what sex means. The meanings can be changed.

Sexed features of the body, genital & reproductive features are a different thing to gender. Mostly we understand gender as masculinity or femininity, that changes over historical time & over different locations. Gender is socially constructed. Most classic queer theory & trans..

..trans feminist writers did not believe gender is innate, biological or born. Read Kate Bornstein, Sandy Stone. It is an absolute travesty that this myth has got such traction, the myth that queer theory says gender is innate & born; no, it says the very opposite.

Because we live in a gendered binary context we are socialised to see ourselves as boys who will be men, or girls who will be women. Children about 7yrs old police each others gender presentation, role, behaviours, assumed appropriate friendships, many excellent scholars have...

..written about how this affects boys for example, depriving them of physical affection with their peers eg hugs & handholding become taboo. Sexism & homophobia play a key role in building gendered men & women. Because of this fierce socialisation, which many ppl think is natural

..it's unsurprising most ppl, not all, come to understand themselves & a key part of their self as being a woman or a man. That's gender identity. Many ppl want to fit in & many ppl feel they fit in. Ppl participate in gender. Plus, sex & gender conservatism is in resurgence.

It's not trans women & trans men designing the pink & blue kids clothes or guns vs dolls kids toys, or selling the ridiculous gender reveal fireworks or buying stupid cards congratulating dads for having a son. That's on you straight, "normal" society, you do you, you do gender.