You seem to have a serious lack of understanding for the terms you use. Gender and biological sex are not interchangeable terms, but individual and specific terms for two different things. Also, even in terms of biological sex, XX and XY are not the only possibilities. Your assertion that no one has changed their genetic coding does nothing for the argument at hand. We dye our hair all the time and it doesn’t change our DNA, so is hair dye not a real thing?