Lumpyoatmeal saidI had a Jewish friend who jokingly said that circumcision in the US was a conspiracy started by Jewish doctors shortly after WWII so that if Nazis ever came to power in the US they wouldn't be able to use circumcision to determine which guys were or weren't Jewish. Although I wasn't entirely sure that he was joking.
I've heard that said, too. But even if some US Jewish doctors were motivated by that purpose beginning in the 1940s, the circumcision movement in the US had begun 40-50 years earlier.
The impetuous appears to have been late 19th Century pseudo-science that targeted male masturbation as a terrible disorder, that would lead to insanity, homosexuality, dissipated lives, a population decline, etc. Not unlike the propaganda that comes from religious conservatives and the political Right regarding homosexuality & gay marriage today.
The quack doctors concluded that removal of the foreskin would discourage wicked & unhealthy male masturbation, by making it more difficult and less pleasurable. This was also the time when anti-masturbation mittens were sold for young boys. Made of the coarsest wool, they were cinched on tightly at night, and could be pinned to the outside of the bed blankets, to prevent boys from reaching down to their "privates".
And returning back to the Nazis, similar nighttime restraints were used on gay men in concentration camp barracks. Along with aversion therapy that SS head Himmler thought would "cure" homosexuals. So that modern gay reparative therapy actually has a long and infamous history.