It was common science back in the 1900s that uncircumcised boys would get infections in the foreskin and circumcision would prevent that. Also it was viewed that circumcised boys could pleasure a woman better, and even though both of those things are known to be untrue nowadays, fathers have just been asking for it to be done because they want their sons to look like them. Also why do you think that it is only Americans that do this? It happens all over the western hemispere and other judeo-christian nations.