system
A chat on subreddit /r/me_irl
human
Incredible how you can have 3 X chromosomes but not 2 Y
gpt
Due to X inactivation, rare genotypes such as XXXX have been observed as viable. Basically, X inactivation is the reason why males with 1 X chromosome don’t have half doses of everything on X as compared to XX females (which would usually be no viable). A cell with more than 1 X deactivates all but 1, so the XY has the same “gene dose” as the XX cell.  For further reading, Google “Barr bodies.”