Human embryos (and probably others) start out female, and grow the male parts a fee weeks later. There is probably someone lurking who can give better details but that's the gist of it. Thats why men have nipples.
Also, it gets much more complicated than that; at least 2% of humans are intersex, meaning they’re a mix of male and female, everywhere from outward presentation (rare) to chromosomal (more common).
It’s not just gender that’s a spectrum: sex is, too. I said ‘at least’ because it’s possible for people to go their whole lives without realising they’re intersex. 2% is huge: if you know 100 people, statistically 2 of them are intersex. Most of us know more than that.
The ‘only two genders’ thing is biologically bullshit. Biology is never cut and dried.
eta: for reference, I have a disorder that’s been in the spotlight lately – Ehlers-Danlos – and you’ve probably at least heard of it. You’ve likely talked to someone who has it recently. It occurs in 1 in 20,000 people. Again, roughly 1 in 50 have intersex traits. I wish this had the visibility it deserves. It’s exceedingly normal.
About the nipples. You’re right in that we all get them by default. As I understand it the only reason males keep them is because evolutionarily it would take more energy to remove them than keep them. Basically we’re all slackers at the genetic level.
There's only around 700 genes in the Y chromosome, with only about 70 actually making proteins. Compare the X chromosome with about 800 protein-coding genes and 20-25,000 total genes.
And the reception of those hormones, which may not exist or may not be functional for some people.
Turns out making beings out of trillions of cells of 100s of types (all of which have basically the same 3 or 6 billion base pair genome, yet have to act very differently) is complicated and any process has many steps, which involve various genes, receptors, signals, etc, all of which could be interrupted.
Only if you're trying to say they didn't have a gender identity yet as fetuses. That's why it's a meme and obviously a joke. Otherwise it makes an interesting point about how silly it is for cis people to base gender on body parts.
correction: 8 days later, I am editing to state I have since learned biological sex is actually undifferentiated in the first weeks of a pregnancy. This is NOT the same as being intersex, but I think an intersex individual would probably have the best perspective to weigh in on whether the joke in the meme still makes sense, due to overlap in the issues it raises. To my knowledge, I am not intersex, so I'll shut up now.
Yes, but since every male person at birth was actually “a female” at conception, that means people who are fine growing up in a male body are actually trans and the ones who want reassignment are just trying to “change back” and are therefore cis (according to the logic in this meme).
IF life begins at conception every one is biologically female because male organs grow much later.
Therefore anyone who is biologically male (by real life standards) and identifies as male is trans because they are actually biologically female IF life begins at conception.
Trans is about how your gender identity relates to their assigned gender. If life begins at conception and you assigned gender at that point, everyone should be assigned female. Anyone who identifies as a man would have a gender that doesn't match their assigned gender and therefore would be trans.