A long-dormant sexually-transmitted virus renders sterile men who have had sex with women. Oh they're not impotent. They still want to have sex. But they can't father children.
This makes straight men kind of like playthings--good for fun but not really serious candidates for fatherhood.
The only ones unaffected are virgins and gay men.
Suddenly nerds and gays are terribly attractive to women. Straight men have become bimbo's.
--E. R. O'Neill