1. Biological sex is fixed before birth, not “assigned” later
People who have stepped away from transition often stress that sex is settled the moment an egg is fertilised. A tiny region on the Y-chromosome (called SRY) starts the body down either the egg-producing or the sperm-producing pathway, and nothing that happens later—surgery, hormones, social labels—can rewrite that blueprint. “Sex is defined by your original developmental pathway. Your origin and design… Breaking down a car doesn’t make it no longer a car.” – ExternalPersonal6059 source [citation:cfeb1a67-1136-4288-b5b8-71597d77e964]
Because the pathway is set so early, they see phrases like “assigned female/male at birth” as misleading; midwives don’t create the sex, they simply observe it.

2. Gametes, not stereotypes, are the north star
Detransitioners repeatedly say the only reliable way to name a sex is to ask which type of gamete the body is organised to make: large, immobile eggs or small, mobile sperm. Chromosomes, beard growth, voice pitch or fashion choices can all vary, but the egg-or-sperm signal never splits into a third option. “Sex is defined by gametes, and there are only two: sperm cells and egg cells. You can’t be both, you can’t be neither (even if you’re infertile).” – die_in_alphabet_soup source [citation:94a75928-71e6-47c9-9c11-ef57dec90ac2]
This focus on reproductive cells keeps the conversation grounded in biology and away from shifting cultural expectations.

3. Intersex conditions are variations inside the binary, not extra sexes
Every body they cite with a “disorder of sexual development” still traces back to one of the two developmental tracks; the disorder simply means the track hit roadblocks. “Most people with DSDs are able to integrate with an understanding of their sex.” – aqua2virgo source [citation:4d08fc49-9688-4cab-825d-e75ba29ac983]
So the existence of intersex people is not viewed as proof of a spectrum, but as evidence that nature can interrupt a process without creating a new category.

4. Infertility, medication or surgery does not swap sides
Loss of ovaries, testes, or hormone production is compared to a broken engine: the machine’s design is still the same even if it no longer runs. “Losing the function of producing these gametes doesn’t change sex either, because it’s defined by your original developmental pathway.” – ExternalPersonal6059 source [citation:cfeb1a67-1136-4288-b5b8-71597d77e964]
This stance helps people grieve fertility loss or medical side-effects without tying their identity to a body’s current level of function.

5. Perception can mislead, but reality stays steady
They warn that mistaking a squat, fluffy squirrel for a cat does not turn the squirrel into a cat; likewise, mis-reading someone’s sex does not rewrite it. “If I guess someone’s sex wrong because of my own bias… Just like if I’m convinced a fat squirrel in a tree is a cat, doesn’t make it a cat, it just means I’m factually incorrect.” – Werevulvi source [citation:b9f0f7e1-0c38-4012-a38c-945eab5c858e]
The analogy comforts people who feel “mis-seen” by others: social mis-labeling is a mistake about reality, not evidence that reality is fluid.

Conclusion

Across these stories, the message is calm and consistent: your sex was set long before you could speak, and no wardrobe, haircut, hormone vial or operation can move you from one reproductive blueprint to the other. Understanding this can feel stabilising rather than limiting; it separates the fixed facts of the body from the flexible terrain of personality, style and behaviour. Celebrate the latter, express yourself freely, and let the former be the quiet foundation you no longer need to fight.