my son penis

Yeah, I'm a little confused as well. At 20 years old, your son is old enough to be making his own decisions. If he wants it, fine. If not, that's his choice.

Now, if you meant 2 years, or 20 months, or something like that, that's a different story. But, even then, most US doctors are not going to perform a circumcision on a child that old unless there is a medical reason for it. Most doctors don't want to do it after a baby is about 2 weeks old. And, nowhere in the US is there a place that will allow you to perform it yourself. It simply isn't safe. There are risks associated with the procedure even when it's done by a professional in a sterile setting. But for a parent to do it, I don't even want to think about the potential for life-altering problems. I heard about a mother who tried to do one on her baby at home, just so she could save the $300 it costs. She permanently and severly injured her baby. This, like any other surgical procedure, is something that only a doctor or highly trained rabbi should do.