A lot vs. Alot: 9 Grammatical Pitfalls
1570s, "one who produces or originates," agent noun from breed (v.). Meaning "one who breeds cattle" or some other animal is recorded from 1530s. Of nuclear reactors, from 1948. As a scornful homosexual term for "heterosexual person," attested from 1986.
A heterosexual person; straight: the scornful term ''breeders,'' used by some urban gays about heterosexual couples with children (1980s+ Homosexuals)