I may be a little older than a lot of the members here, and therefore have seen some very frightening changes. Too many young Catholics are leaning from society that homosexual activity is okay. It most definitely is not. There are two main aspects: The sinfulness of it, and the pyscological disorder.
1) The sinfulness of it is plain and clear from the Bible and the Catechism. Some folks try to distort what the Bible says and cherry-pick what the Catechism says to excuse it, but homosexual sex is inexcusable. This does not mean we should hate homosexuals, but as with any mortal sin, you love the sinner but hate the sin.
2) Same sex attaraction is a disorder, not only accordiong to the Catechism, but according to the American Psychological Association (APA) for most of its history, until recently.
For some folks though, this disorder is now the "non-disorder formerly known as disorder." It was a disorder in the DSM I and II published by the APA. But in the last publication, DSM IV, it was removed as a disorder. Why?
Protests by gay rights activists against the APA began in 1970 when the organization held its convention in San Francisco. The activists disrupted the conference by interrupting speakers and shouting down and ridiculing psychiatrists who viewed homosexuality as a mental disorder. In 1971, gay rights activist Frank Kameny worked with the Gay Liberation Front collective to demonstrate against the APA's convention. At the 1971 conference, Kameny grabbed the microphone and yelled, "Psychiatry is the enemy incarnate. Psychiatry has waged a relentless war of extermination against us. You may take this as a declaration of war against you." To put is bluntly, the American Psychological Association buckled and caved to protestors, and therefore have no legitimacy now.
So the APA can be, and is, wrong. The current APA thinks that they were "wrong back then," and "right now." But certainly, the opposite can be true, that is was right back then and wrong now. I think that they were right before and wrong now because they now fear liberal retaliation and politcial correctness that did not exist before.