The thinking, and this is communicated very directly to the young men, is that if you don't participate, you're gay. You're effeminate. You're not a real man. You never mature from being a boy to being a man.

Most forms of FGC are decidedly harmful, and pediatricians should decline to perform them, even in the absence of any legal constraints. However, the ritual nick suggested by some pediatricians is not physically harmful and is much less extensive than routine newborn male genital cutting. There is reason to believe that offering such a compromise may build trust between hospitals and immigrant communities, save some girls from undergoing disfiguring and life-threatening procedures in their native countries, and play a role in the eventual eradication of FGC. It might be more effective if federal and state laws enabled pediatricians to reach out to families by offering a ritual nick as a possible compromise to avoid greater harm. (source: PDF; not safe for work, contains line drawings of female genitalia.)