The writers and producers of the show would have us believe that Dean is straight. He seems to be honestly attracted to women in a sexual way so he isn't gay, no. However things like his reaction to Dr. Sexy and the case of the siren choosing a male as the attractive form to lure Dean with (as opposed to a women with other men) hint that he may not be entirely straight.
How you read it is up to you, there are people convinced that Dean is bisexual and with good reason. Will that ever be cannon? Who knows, but sadly it doesn't seem likely.
Dean Winchester has no children.
If a man is gay then he's not bisexual, then he's gay. Right?
gay
In an episode where Dean Winchester was not a hunter, he was a mechanic.
No he is not gay or bisexual. He is straight.
Just one: they can ask the patient if they are bisexual or gay, and if the patient answers yes, then they are bisexual or gay.
bisexual
She is Bisexual
No. Bisexual, gay, and lesbian are sexual orientations, not genders.
Gay
Not necessarily, they find interest in both women and other men
It is not advised that you ask a person if they are "gay, bisexual, or just paranoid," as this is rude.