No, you don't get it. It doesn't matter if it's possible to "figure out a gene therapy"; anti-gay bigots will simply use any claim about the biological roots of homosexuality to reinforce their preexisting belief that homosexuality is an aberration. --And just as genetic flaws like myopia can be "corrected" with contacts or glasses, the genetic flaw of homosexuality will be corrected (with a little help from God). Don't you see that it doesn't matter whether or not you or I think this perspective is stupid? It's important to recognize that within the gay-bashers' culture, "curing" gays is not cruel, it's the work of God, and saying that homosexuality is biological won't change that ideology.
Also, the concordance in twin studies does not provide a "compelling case for homosexuality's biological roots"; in fact, it demonstrates that sexual orientation is not genetically determined. Yes, the concordance rate for gay/lesbian sexual orientation is higher for monozygotic twins than it is for dizygotic twins; that suggests a genetic influence. However, the concordance rate for monozygotic twins--genetic clones!--is only around 50%. This means that I can be a genetic clone of a gay man, and I am just as likely to be straight as I am to be gay.
I gotta preach it again: this whole "root" or "underneath" metaphor for biology has been contradicted time and time again by research on human behavior patterns, including sexuality. Sexuality is a product of a complex interplay of genetic, biological, psychological, social, and cultural factors (did I leave anything out)? There's no "root" here to discover, just the strands that make up the patterns in the behavioral fabric.
Miles