> > I have a theory that when a "pet" form of an English first name ends in a "y", then it's a man, but when it ends in an "i", then it's a woman. Could some native English speaker confirm or deny this theory, please?
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> No, as "Kimmy" and "Becky" are both female. I'm not sure how well it works with Terr(i|y). "Terry" seems to be used by both, but all the Terris I know are female. Luci and Lucy are female. I'm not sure there is a Grand Unifying Name Theory.

According to this, only the "i=female" part of my theory works, the "y=male" part does not. Thanks for the information.