Reply to sibling comment -- perfect pitch can probably be developed with a lot of training (though I imagine it's harder if you're not a kid anymore... for kids, sure -- there are tonal languages, after all!).
But it's honestly not that valuable a skill, even for professional musicians. Having really keen relative pitch (and avoiding slipping pitch if you're singing, for example) would be a much better focus to take.
What is the relationship between perfect pitch and tonal languages? I've dabbled in Mandarin and there relative pitch seems to be good enough. But I realize that there are tonal languages other than Mandarin, and I know nothing about them...
But it's honestly not that valuable a skill, even for professional musicians. Having really keen relative pitch (and avoiding slipping pitch if you're singing, for example) would be a much better focus to take.