Is it unusual that my younger brother is more muscular than I am?

@drymer He was stronger than me before that, he could beat me at arm wrestling as a when he was 12 and I was 14, is that unusual?

@JimFarris16 Unusual but not impossible.

@drymer I think it was more like since he was 10 and I was 12, I seem to remember being excited that he was stronger than an 7th grader even though he was only in 5th grade.