Gays, Genes and Lefties Who Proclaim Fealty to Science

I thought lefties were into science and all.  Back to that in a minute.

Apparently there is a kerfuffle because Ezra Klein hired a gay guy who is not sufficiently or appropriately (can't tell, and don't want to) gay.  Deroy Murdock has some skinny.

“Judging from the reaction, you might have thought Ezra had hired Rick Santorum,” wrote columnist Andrew Sullivan. As Robert Stacy McCain details on The American Spectator’s website, Ambrosino has become a heretic for not echoing the liberal “gay = DNA” incantation. 

Why is this important?  Because it is.  Here is why.

The gay-rights movement advances the “born gay” hypothesis. If gays pop out of wombs that way, the argument goes, equality will cascade forth like Iguazú. If being gay is a choice, however, the public and politicians will respond: “Eeeeeeeeew, gross! Shut up and get back in the closet!” Bye-bye, gay marriage. Hello again, Don’t Ask, Don’t Tell.

Murdock points out a few reasons for gays to not want to toe that line, good points too, but this is what I want to know - how can homosexuality be genetic and evolution be true?  Except for the small number of homosexuals who procreate before fully embracing a homosexual lifestyle and those who conceive through modern fertility science, homosexuals do not pass down their geteric line.  All told, homosexuals certainly do not achieve replacement rate procreation.  If you believe in evolution, the "gay gene" would disappear over time.  So which is it?