There were many recent headlines about a study suggesting that homosexuality stems not from genetics, but epigenetics. The original study hasn’t been released, except perhaps to io9.com, which has a story seemingly more complete than the abstract or press release of the study on which it is reporting. Sheepcat has an excellent, long post on the issue and what the study says and doesn’t say, what it means and doesn’t mean.
The key issue is moral, not scientific. Genetics and epigenetics do not dictate behaviour; a predilection, whether it be same-sex attraction, alcoholism, a propensity for violence or whatever, is not an inevitability. Sheepcat says, “We’re not responsible for our desires; we’re responsible for how we act on our desires. This study doesn’t change that.”
Sheepcat also addresses how Catholics (and all Christians) should respond, namely by recognizing the intrinsic dignity of every individual regardless of their sexual inclinations.