A common manifestation of obsessive-compulsive disorder is one called homosexual OCD (HOCD), also called gay OCD or homophobic OCD. This arises as a fear and obsession with being gay - usually a person who believes him or herself to be straight will question that sexuality and begin obsessing on homosexuality.
Here's the one thing that a counselor will remind you as soon as you begin treatments for HOCD: if you believe yourself to be straight, then you are.
The instances of a straight person "finding out" they're gay through HOCD episodes are so statistically small as to be less than flukes. They're almost non-existent. Most of those who "convert" to homosexuality do so only temporarily as they begin to understand that their obsession was not about their own sexuality, but about other fears and anxieties that may not have even been related to homosexuality.
Several gay people have participated in the forums here at BrainPhysics and one of them, wrote an extremely insightful and useful article here. The following is an important quote from that article:
I know that I am gay, but I have only ever gotten hard with girls. This must be because I am in the closet, and I know that I'll suddenly get hard with guys once I come out. But the thought of being with another guy makes me sick. Damn, gay stuff is so disgusting! I'd never want some naked guy to touch me that way. But my mind tells me that this is what I want, and that I'll be O.K. with it once I come out because I am gay. But I'm not gay! But my mind tells me I am. Dammit, why won't my mind shut up? I do all this checking by looking at gay porn, and I still don't know what I am. But I just want to look at hot women instead. I have never been attracted to guys, but I know I am a gay guy. This anxiety is killing me. I can't even hear the word gay without becoming anxious.
This was an example of a straight man suffering from HOCD and examining whether or not he is gay. If it sounds familiar to you, as an HOCD sufferer, then you know you're not alone.
Now compare those feelings to a gay man who is "in the closet" and has not admitted publicly that he is gay:
I know that I am gay, and I have only ever gotten hard with guys. I am in the closet because I am afraid people will reject me, yet I have always wanted with everything in me to fall in love with another man who loves me back. That would be so beautiful. I was taught that gay stuff was disgusting, but when I think of being held by a man I get butterflies in my stomach. When I see a guy I like, it just feels right. The only anxiety I feel is over what others think of gays and how I think I'll be treated by straight people in power if they find out about me. I don't feel any anxiety when I think about how lucky gay guys who are out of the closet must be, and I wish I could be like them.
See the profound difference between the two? One is worried that he "might be gay" yet has no sexual or physical desire for other men. The other has plenty of desire to be with other men, but social anxiety over doing so.
If that doesn't illustrate things, then nothing else will. Just because you are anxious about being gay doesn't mean you are gay.
If your obsession centers around whether or not you're gay instead of on whether or not friends and family will accept you as gay, then you're not gay.
That, friends, is all you need to know.