There are quite a few possibilities, from new arrivals to a villager being made young again. I never give up until the game makes me give up.

I usually get a long line of either one gender or the other. It's always worked out in the end though. (Except for one game but I neglected it for too long - so don't do that!)

For a very long time, the children born to my villagers were male, including two sets of triplets! I would get approximately one girl for every fifth male born. It gradually began to even out, however, and now it's about equal. So, hang in for a bit. As Lady C says, there are events that can help you greatly! It's not over 'til it's over!!

Change your option to "easy". Then you'll get 50/50. Too bad there's no way to adopt kids, say after a parent dies, etc. Eeeww; nevermind; that's too realistic! Who needs that?? Forget I said anything about adoption. LOL