I am 29/f and I'm anosmic (meaning I've never been able to smell), AMA
Some context: I have a rare hormone disorder called Kallmann Syndrome (which affects 1 in 40,000 women and 1 in 10,000 men). Among other traits - some specific to men, and most of which I don't exhibit i.e. cleft palate and kidney loss - the main factors are delayed puberty (treated with HRT) and congenital (from birth) anosmia (untreatable and irreversible lack of smell).
While "anosmia" or "hyposmia" (reduced ability to smell) can be treated in some cases, mine will never be and is caused by underdeveloped olfactory nodes.
Feel free to AMA about anosmia or KS, or tell me something weird about smell that I may have never realised.
Hard to prove a lack of smell, that would be why my mum didn't believe me until I was eighteen, but I did make a video about this a few years ago and it got a few comments from other anosmics: https://www.youtube.com/watch?v=Ejjox-JOGSo