I am 20. Why is my 14 year old brother stronger than me?

I'm female, 20, and I'm in pretty good shape. I go hiking, play varsity soccer, and work out. I'm pretty strong, for a girl. But recently I was wrestling with my little brother and he completely manhandled me. He pinned me down and I absolutely couldn't move. It shocked me. I used to toss him around since he was a kid, but now all of a sudden he's stronger than me at 14. Is he strong for his age or are guys that much stronger than girls? Suddenly I feel a lot more vulnerable out in the world lol.
I am 20. Why is my 14 year old brother stronger than me?
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