Well first and foremost, the American Psychological Association is not the only mental health association that says that homosexuality is not a mental illness, choice, or abnormality, and that homosexuals hardly, if ever, become heterosexual.
Far from it. You also have:
American Psychiatric Association
American Counseling Association
American Medical Association
American Psychoanalytic Association
American Association of Pediatrics
National Association of Social Workers
National Association of School Psychologists
Now that that is out of the way. NO they were not taken over by gay activists or lobbyists. Do you honestly think that a MINORITY could influence the professional decision of over 500,000 mental and medical health professionals? If these mental health organizations were ones to cave into activism, then why isn't homosexuality still a mental illness?
I mean, with how many people are against homosexuality, and who fight so hard just to say that homosexuality is abnormal, homosexuality TO THIS DAY is STILL not considered a mental illness!
Anyone who says otherwise, is therefore wrong. It's just another one of their ridiculous claims they use to forward their gay-hating agenda. Plain and simple.
Soulforce, "What the science says -- and doesn't say -- about homosexuality": http://www.soulforce.org/pdf/whatthesciencesays.pdf
Soulforce, "A Falso Focus on my Family": http://www.soulforce.org/pdf/whatthesciencesays.pdf
Now Soulforce is a LGBT rights organization, but the sources they cite ARE credible, academic sources from those mental health organizations. You're encouraged to research if you are in question of them.
I also encourage everyone to take a look at this video, "Not a sin, Not a sickness" also by Soulforce: http://www.soulforce.org/article/homosexuality-debate-verdict-video