Keating has this wrong. The Vatican issued a definitive statement some 10 or 15 years ago, and they said that homosexual acts are always wrong and sinful, while a homosexual inclination itself was an intrinsic disorder. Any homosexual leanings represent an intrinsic disorder, not just the fulfillment, which is de facto mortal sin, and thus beyond being just a disorder.
This is only confusing when (like the priest of Britain) one knows nothing of original sin. Just think in terms of original sin: concupiscence, weakened will, darkened intellect, disorderd passions. This perfectly explains why people may be born with homosexual inclinations, just like some people have a greater tendency towards all sorts of other crimes like alchoholism, kleptomania, pedophilia, pyromania, etc. All of us have inclinations towards some sins.
The Catholic position is the opposite of the gay slogan "God don't make no junk." The Catholic position says that we are all born in original sin and deserving of eternal punishment. It is only through the extraordinary act of redemption that we can be saved.
Kearing is correct and he cited the Teaching of the Catholic Catechism. If you have a Document proving the Living Magfisterium wrong, produce it.
No one is born with homosexual inclinations. Homosexuality is caused by mental trauma due to molestation, absent or insufficient relationship with one's father or by relentless teasing by ones peers during the formative years. The vast majority of cases are caused by molestation.
Of the other diseases you mention, only alcoholism has a genetic component. All the others are similarly caused by trauma of some sort.
The first law of Homosexuality:
"Homosexuals" don't reproduce, they recruit