I'm not a guy, so not sure if I should be commenting here... but it looks like your post on the other sub was actually removed, possibly for trolling?

But, in case you are serious...

If race is not real and is a social construct because we share most of our genes, if not all of our genes, with each other, then how can biological sex be real and not be a social construct when we share most if not all of our genes with each other?

This is faulty logic.

• Fact: humans share over 99% of DNA with each other
• Fact: there are few meaningful group differences between a) racial demographic groups but there are MANY meaningful differences between b) sexes/genders.

Just because something is true for one set of demographic groups (race), that is not necessarily true for another set of demographic groups (sex). (You would have had to prove a link between those two in order for this quoted argument to mean absolutely anything.) Yes there is a handful of interesting health differences between racial groups, but that doesn't say anything about sex group differences. You can't just map your assumptions about race onto sex.

Now, what do we know about sex?

• Sex is differentiated by the type of gamete a person is theoretically able to produce (and thus, reproductive systems).

That's it. Full stop. Sometimes a person is unable to sexually reproduce because of circumstances inhibiting their ability to do so-- we don't say that a male wearing a condom is not male, for example, or that a woman rendered infertile by the effects of having Turner's syndrome (one X chromosome) is not female. Those people still have a set of reproductive organs, even if they are not functioning the same as everyone else's. (If you want to see an interesting case of a woman who doesn't have a vagina-- but is still a woman who has ovaries and uterus-- https://www.livescience.com/amp/60162-born-without-vagina-mrkh-syndrome.html )

This is an observable, objective group differences between sexes, that you see OVER AND OVER with every single person on this planet. And in the vast, vast majority of cases, there are a bunch of corresponding health, physiology and external appearance differences that go along with it. Do you not think that the fact that some humans have uteruses and others don't, is not a "real thing" and is a social construct? Because that's what the word "sex" is used to observe. A fact.

Finally:

We share at least 80%-90% of our genes with each other ---> race is a social construct and is not real

We share at least 80%-90% of our genes with each other ---> biological sex is a social construct and is not real ...

Okay, this is just straight-up laughable.

• First, neither of these are "equations" as you said (you have defined no equalities). You have a claim/premise in each one-- a "fact" about DNA-- but your conclusion drawn from the premise is invalid. There is a name for this type of mistake in Logic 101 course, I suppose I'll google it.

• Your fact itself is wrong, humans share way more than 90% of their DNA with each other.

By your own logic, this is also true:

"We share at least 80%-90% of our genes with each other ---> age is a social construct and is not real"

Do you think age is not a real thing?

Just because humans share DNA, does NOT mean that humans are homogeneous and that there are no subgroups within humans.

And-- humans have to reproduce somehow. We do not reproduce asexually. Because of that fact, we have two sexes.

edit: typo