Heterosexual men who get the snip cut their chances of contracting HIV by more than half, since the foreskin is delicate and tears easily.

Many parents think foreskins are hard to clean, says Georganne Chapin of Intact America, a group lobbying against infant circumcision.

Circumcision helps prevent HIV infection because the foreskin, which is removed during the procedure, has many cells that are HIV targets, the researchers explained.