I’m still in my 20s, but as of a few years ago I started forgetting what’s my exact age. I always have to stop and recalculate it each time someone asks me. I get asked fairly infrequently, but when I do it’s a bit weird/embarrassing that I have to say “wait, let me calculate”. (I know when I was born, of course.)
It seems as if there’s no good reason I’d remember it, since it changes all the time and it is rarely mentioned in practice. But others, including people much older than myself, know their own age immediately.
I’m also terrible at remembering people’s names, I don’t know if that could be related?
After 40 it no longer really matters. Old people or people your age don’t like talking about our age because it reminds us that we’re at the back end of life. And young people just automatically look at us like we’re old … because we are!
Whenever someone asks me now, I just tell them I don’t know. And if they insist, I give them a number anywhere from 45 to 49. And once I reach 50, I’ll just tell people I’m old and not to bother me about it.