Generally no, boys don't really start developing good until around 13-14 or so. I don't know how small you are talking about though... but if you do feel it's not correct, then taking him to a peds urologist would be the best Doctor.
I have a son too and at around 12 he was small (enough for me to think thats not good) and sure enough.. around 14 it changed..
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Healthcare Expert
17+ years, Healthcare Expert