I keep seeing people post this but there’s a huge misunderstanding of biology and embryonic development there. First, “sex” isn’t binary—what makes up a “sex” is a collection of sex characteristics, that includes stuff like chromosomes, genitals, hormones, and so on, that tend to cluster into a bimodal distribution. “At conception” there are literally no sex characteristics other than chromosomes, but they know they can’t just say those because people can be intersex with sex chromosomes other than XX or XY, and some intersex people can have genitals and other sex characteristics that don’t match up to how they want to box them in, so they’ve started going by this bs “produces large or small gamete” definition, which is more “binary” than most other definitions. But not everyone even produces gametes due to infertility or surgeries.
The whole executive order doesn’t make sense because “the sex that produces the large/small reproductive cell” is not only not a well-defined sex (reproductive cell production is one sexual characteristic out of many), but “at conception” you can’t say what reproductive cells, if any, the embryo will produce. When people say “this means everyone is female!”, that’s not true either, as while divergence between sex characteristics other than chromosomes happens later, there is no “female body plan” they follow—they branch off in different ways and once again there are multitudes of combinations of characteristics that happen.
Put frankly, you cannot sex an embryo at conception in any way that’s going to put everyone into two neat boxes the way that these fascists want to, no matter how they word it, nor does it make sense to say all embryos “start” as female and then “male” development “turns on” for some. I really wish more people understood that sexual characteristics are not necessarily tied together and what we deem someone’s “overall” sex to be is a social construct.
I suspect that the reason (outside of absolute ignorance) they put “at conception” in these orders is because they are trying to shove anti-abortion rhetoric into it as well