The broader culture has undoubtedly influenced the increased questioning among American Jews about circumcision.

Since 1979, the national rate went down 10 percent overall (or 6 percentage points, to 58 percent). The region with the steepest drop by far was the West, where the overall percentage of newborns circumcised went down 37 percent, to 40 percent.

Especially in the Northeast and Midwest, circumcision has been the mainstream American thing to do. American Jews didn’t have to consider as a factor the possibility that their sons would stand out.

While it’s unclear if the rates will drop further, or rise, the mere possibility raises the question: Would this highly assimilated group of Americans, who in high numbers reject other barometers of religiosity like synagogue membership and belief in God, continue circumcising if they knew it would make their sons look different?

“I’d bet my house on this: As America goes, so will circumcision. If America starts turning against this, give it one generation,” said Shira Stutman, rabbi at the millennial-focused D.C. synagogue, Sixth & I.

Ben Rempell, a 35-year-old government contractor who felt adamant about circumcising his two sons, said he couldn’t say for sure if his calculus would be different if Jews were the only ones to circumcise.

“Maybe,” said Rempell, who moved overseas from the U Street area a few years ago. “If there was enough knowledge to know he’d feel really uncomfortable and if it were to affect his growth and development as a person I might consider not doing it.”

Tradition, culture and health trends factor into decisions around the world about whether to circumcise. While circumcision is becoming more common in some countries, including Africa, it is becoming less so in Europe, where lawmakers in some countries have unsuccessfully pushed to ban the practice. It isn’t common in South America or parts of Asia, from where many new Americans come.

It’s unclear what will happen with global circumcision rates. Muslims worldwide also circumcise, and experts on American Islam say there is no questioning of the practice among Muslims here.

Rabbis know the practice is being questioned in an unprecedented way, and are using a wider range of arguments to support it.

Rabbi Julie Pelc Adler, head of the circumcision, or brit milah, program for Reform Judaism, frames circumcision as a way to remember the power of procreation. “The point isn’t to curb sexual enjoyment but to remind them to use it with love and not hate,” Adler said.

Even the Web site of Chabad, a major movement of Orthodox Jews, characterizes circumcision as a “human act. This teaches us that our spiritual, emotional, moral and ethical perfection requires human effort. God cannot do it for us.”

Adults attending conversion classes at Sixth and I synagogue learn about the traditions behind the ancient Jewish practice of circumcision. (Michelle Boorstein, Linda Davidson and Sandi Moynihan/Michelle Boorstein, Linda Davidson and Sandi Moynihan/The Washington Post)