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Gender is an individual's perception of (among other things) their sex. Sex is which chromosomes they have. For most mammals, that's XX for females, XY for males, or any of the (rare) aneuplodic sex chromosomal abnormalities like Kleinfelter syndrome (XXY, e.g. male calico cats), or (rarely viable) chimeric individuals where two embryos fused in the womb. For some mammals (a few bat & rat species), most arachnids, and many insects that's XX for female and just a lone X for male, and any aneuplodic abnormalities of the sex chromosomes that aren't fatal result in an abnormal female. For birds, most reptiles, some insects, some fish, some crustaceans, and some plants, that's ZW for female & ZZ for male, with similar complications to the XY system. Sex is pretty simple. The vast majority of the time for humans, it's either XX or XY. Which (primary and secondary) sex organs someone has is more complicated, because that can be altered. But it's still pretty simple, if not always what one would expect from the chromosomal sex. Gender is complicated, because it's entirely social. It's not entirely clear which animals even have gender. Sexual attraction is also complicated. The factors which determine it aren't well understood. |