Means you can have them over to dinner and not worry about your wife and kids. They are normal in every sense of being a man just more so. I would bet 1/3 of Pro athletes are XYY. Fro boy is more likely XXY.
“Testosterone levels (prenatally) are normal in 47,XYY males.[9] Most 47,XYY males have normal sexual development and have normal fertility”
Doesn’t seem to support your hypothesis.