Honest question here: are there trans men that want to get pregnant? What fraction of trans men want to get pregnant? I get this is tangential to the discussion and I get I am betraying my ignorance, but it is not particularly easy to find information on this question and it seems somewhat pertinent to the practicalities of this issue.

Yeah, there are men who want to have kids. Many such cases.

Are you purposefully misphrasing my question? Most men want to have kids, everyone knows that. That is very different from a trans man that wants to have kids by being pregnant themselves, after they have gone through all the hard work necessary to live their life as a member of a sex that can not have kids. I am absolutely incredulous that there are *many* trans men that want to be pregnant.

A good time to learn something new!

Gender is a pure social construct (e.g. man, woman) and sex is more biologically derived social construct (e.g. male is xy, female is xx). But this doesn't cover all of the known sex chromosome phenotypes, hence there's still a strong social component here too.

I think that depends on your view of sex and what's more important about it. If you view reproduction as the most important (or foundational I suppose, I'm not a philosopher I don't know what this stuff means) aspect of what sex is, there would be two sexes, male and female. If you want an exact representation of all theoretically possible combinations of phenotype and genotype, including everything from surgery to accidents/birth defects and environmental conditions to intentional genetic modification, you are going to have to create a pretty sophisticated "sex" theory (in the scientific sense), but that's not what most people mean.