Primogeniture in any form is discriminatory precisely since birth order is an immutable, permanent, unchosen characteristic assigned randomly at birth, just like race or sex.
replySex is mutable but good try
replyGender is mutable. Sex is determined by genetics, though in a handful of creatures, sex could be considered mutable.
replyYou're right, but there was an article on here in the last week about genetic therapy correcting Down Syndrome.
replyI wonder how long before sex does actually become mutable.
You can change sex
replyAnd people can be born intersex
Your data is wrong