Oh, that is just too funny! I also wanted to be a boy when I was a kid...in fact my childhood "profession of choice" was being a cowboy.
I still remember the day when my aunt decided to sort me out and told me that I could grow up to be a cowgirl but could never be a cowboy. Well, I sure sorted her out fast and let her know in no uncertain terms that there was no way I was going to be a cowgirl and wear those stupid skirts, nope - I would be a cowboy so I could wear jeans all the time and would never have to wear a stupid skirt again in this life!
This aunt still insisted that I could not ever be a cowboy. Well, she was right in a sense....turned out I really didn't care all that much for cows. So I grew up to be a sheep farmer instead. And I live in my jeans

40 seems to be the age for serious rethinking of the decision not to have kids. I don't know why this is so, but it is. Perhaps it's the old biological clock ticking that triggers this rethinking. Perhaps it's the feeling of a door closing on an option taken for granted until then. Be that as it may, I think it's normal an healthy to rethink from time to time.
For me, I never liked being around kids even when I was one and never, ever wanted to have anything to do with babies. Never enjoyed playing with dolls - boring. My favorite toys as a kid were my ranch set, my horse collection, and my guns. Other than that, I was busy reading and had a love/hate relationship with the local librarian - she loved that I read, hated that if seh tried to keep me confined to the kiddie book section I'd tell my mother and my mother would go down to the library and give her holy he** for censoring my reading.