Well, of course homosexuality hasn't been filtered out of existence. Mules, by and large sterile animals, still exist, but they don't procreate. Likewise, homosexuals enjoy an existence as mules; they do their thing, but pass on nothing biological. Similarly, like mules, these folk are an aberration.
"Medical" science, as a raison d' etare, is kinda funny, too. Prior to 1971, the APA considered homosexuality a neurosis on par with transvestitism and Turet's syndrome (sarcasm); then the association "grew." Miraculously, with a governing board of homosexuals, the APA discovered that homosexuals were mainstream folk after all. Viola! Stroke of the pen, law of the land.
Well, hey, why stop there? Let's forget about anything we've learned since the good old days. Why don't we teach that the sun revolves around the earth. Prior to 1632 the world considered that to be the gospel truth (literally). The church finally came around to exonerating Galileo for his audacious theory in 1992. Prior to 1892, most of the U.S. didn't consider Afican-Americans to be biologically human. They considered them to be on par with a dog or a mule.
Why don't we just go back, huh?