Many of the castrati’s well-documented personality disorders were a direct result of their disfigurement, as well as their inability to lead normal sex lives. They were neither man nor woman, but something in between.
Unfortunately, children are not meant to be stars. It ruins their development into normal adults. His self-image came from his singing. Probably around the time of his ballad to a rat, "Ben," his everything was wrapped around that perfectly tuned, sweet voice. Somehow, he must have gotten someone to help him avoid his worst fear: puberty. I have no idea whether he got some cruel doctor to literally castrate him or whether he managed to have it done chemically, but he never did lose his high voice.
I remember as a child seeing a film about the Viennese Boys' Choir. Each boy dreaded that day when his voice would finally crack, for it meant his time with the choir was over. I think Michael could not bear to give up that voice that millions loved him for.
His characteristics do indeed meld perfectly with those of castrati. I do not believe you will find his DNA in those children of his.