For me, having kids caused me to forget my age. I remember my two boys age, and my wife’s age, but often forget mine. The other day I was trying to think how old I was when my first son was born, and had to do the math. My age isn’t something I think about.
Except for this year, when I turned 30, which sucks enough that I can remember it. I’m sure I’ll be thinking I’m 30 for many years to come.
This thread astonishes me. I always know how old I am: 74 currently. Perhaps as a mathematician, numbers have a better hold on my mind.
Wow I love this thread, I feel so much less alone.
I always have to do the math. It’s just not that important for me.
I have to say, I totally understand forgetting that you’ve turned a year (or years) older and thinking you were younger than you are…but I don’t understand thinking that you’re older than you actually are.
I’m 33 but I’ve caught myself almost telling people I’m 31 because I haven’t made any deal about my birthday for a while and haven’t practiced saying in my head, “Now I’m [my new age]” like I used to do as a kid. But why would I mistakenly think I was 34? I guess that’s one brain glitch I don’t have! Whew. 
I have been 34 for three years. Funny thing is, I won’t be 34 until later this year.
I just don’t care how old I am.
Hell, I’m 62 and my brain still insists I’m 23.
I did completely forget my 32nd birthday, however. I was overseas and didn’t even think about it until nearly a week later.
I generally only forget my age when I meet a lady much younger than myself.