Except XX and XY aren’t the only combinations. There is just a single X, XXX. XXY, and XXY.
And then there are just plain intersex individuals who produce both or neither reproductive cells. Chromosomes may not express themselves properly.
Biology isn’t as simple and clear cut as you make it out to be.
And the only reason they used “at conception” is to signal that life begins at conception for the abortion argument. The executive order doesn’t actually have anything to do anything with science, it only tries to use it as an excuse for their anti-trans beliefs.
Maybe someday I’ll be a millionaire. Hopefully it won’t be at the same time a loaf of bread is $100 and a million dollars is poverty.