mid-14c., "discharge of semen other than during sex," later, "desecration, defilement" (late 14c.), from Late Latin pollutionem (nominative pollutio ) "defilement," noun of action from past participle stem of Latin polluere "to soil, defile, contaminate," from por- "before" + -luere "smear," from PIE root *leu- "dirt; make dirty" (cf. Latin lutum "mud, mire, clay," lues "filth;" Greek lyma "filth, dirt, disgrace," lymax "rubbish, refuse;" Old Irish loth "mud, dirt;" Lithuanian lutynas "pool, puddle"). Sense of "contamination of the environment" first recorded , but not common until .
The taboo seems to have lifted for second cousins. Notes in "Of Maeglin" in the Silmarillion imply that this twist of Maeglin's was part of the curse of Mandos upon the Noldor. Notes in Morgoth's Ring imply that, if you were first cousins but your uncle was your father's half-brother, this abrogated the incest taboo enough that marriage was an option. Further notes to LACE, strangely following the footnotes (page 234 in my copy) discuss other incest-taboo overlap possibilities that beautiful immortals have to worry about. "None of the Eldar married those in direct line of descent, nor children of the same parents, nor the sister or brother of either of their parents; nor did they wed half-sisters or half-brothers." (LACE)
In September 1970, Harper's Magazine published an article by Epstein called "Homo/Hetero: The Struggle for Sexual Identity"  that was criticized for its perceived homophobia .  Epstein wrote that he considered homosexuality "a curse, in a literal sense" and that his sons could do nothing to make him sadder than "if any of them were to become homosexual."   Gay activists characterized the essay as portraying every gay man the author met, or fantasized about meeting, as predatory, sex-obsessed, and a threat to civilization.  In the essay, he says that, if possible, "I would wish homosexuality off the face of the earth", a statement that was interpreted by gay writer and editor Merle Miller as a call to genocide .  A sit-in took place at Harper's by members of the Gay Activists Alliance .