You forgot one possibility: your figure is wrong.
Add that possibility to the equation and do a Google on the words "Occam's Razor".
You'll have to address your concerns about 73% of 'gay' males admitting they had sex with boys to the authors of the subject study. (Who also happen to be 'gay')
I've not seen anywhere where the study is disproven.
Quoted from the article:
"A controversial study has demonstrated that homosexuality is not necessarily a fixed sexual orientation, but that "gay" men and lesbians can change.
The research was conducted by Dr. Robert L. Spitzer, who in 1973 was one of the driving forces behind the psychiatric community's removal of homosexuality from its manual of mental disorders. The study was published in the October Archives of Sexual Behavior."
Note that Spitzer was the one who got the disease delisted in the first place. Even he now recognizes it as a changeable (curable) behavior choice