However, in terms of self-destructive behavior, which here is the engagement in homosexual or bisexual activities out of a rejection of the perceived wrongdoings something (Not necessarily the institution of heterosexuality - this 'something' could be anything; just as heterosexual perversion occurs from a rejection or misconception of perceived realities, which aren't necessarily perceived realities of sexual things.) has done to the subject: This form of sexual deviance is the result of a psychological disorder, and should be handled as such. Neither acceptance nor rejection of sexual activities formed out of self-destructive behavior should occur from the friend's end of the table. If it is a truly harmful self-destructive behavior to the individual, they should seek help just as any 'sex addict' would.
For those who have 'been so for as long as they can remember', they aren't ones to convert anyway. Since there's little purpose in risking your friendship with the person because of something they believe they were born with, you should just accept the person here as well.
It should be noted, though, that it is in fact not a fact that people are born gay, lesbian, or otherwise. There are no specific details in the hormonal imbalances that would cause changes in sexual orientation for a person, no less any evidence to provide the role such imbalances would play in a person's sexual orientation. While I do not find it inconceivable at all that hormonal imbalances or genetics play a role, the argument that this is the single cause of a person's intrinsic non-heterosexuality is a half-truth. Also, there are no fair studies that show clear evidence that people are intrinsically non-heterosexual; any evidence that may arise in unbiased studies (which does occur, but it rare) fails at attempts at replication or fails under critical scrutiny.
"Dr. Gregory Dickson, whose doctoral thesis is on the relationship between a mother and son in the development of homosexuality, found that 49% of the homosexuals he surveyed said they had been molested, compared to less than 2% of heterosexuals." -http://www.freerepublic.com/focus/fr/724179/posts
"Homosexual researchers Bailey and Pillard conducted the famous "twins study" quoted by homosexual activist groups to promote the idea that being "gay" is genetic. The study found that among those twins studied, the researchers found a rate of homosexuality of 52% (both twins homosexuals); 22% among non-identical twins; and a 9.2% rate among non-twins.
This was hailed by homosexual activists groups and by the media as supposedly proving that homosexuality is genetic. The study actually proved the opposite. As Byrd, et al, note: "This study actually provides support for environmental factors. If homosexuality were in the genetic code, all of the identical twins would have been homosexual."" - http://www.traditionalvalues.org
You are not naturally homosexual or bisexual. You definitely may have more of a tendency to be so than others, but there is no such thing as a naturally-born homosexual or bisexual. External factors dependent upon interpretation by the individual are what decide a person's sexual orientation, to varying degrees depending upon the individual's genetics and hormones. Saying otherwise is absolutely baseless.