I always looked young for my age. I had a cousin (now deceased) who was the exact same age, to a couple of days, and when we were 15 he was getting hit on by college girls and I looked 12, at most.
In my 40s I had a friend 10 years younger, who looked wiser than his years, and people though he was older.
Now in my (still) mid-50s, things are catching up. I just went back to the States for a family reunion, and we’re all getting old!