Well, it doesn't really work like that. My folks were both straight and I turned out gay, and there are hundreds of gay fathers and lesbian mothers out there with straight kids.
If anyone wants some facts and research, check this link out:
http://www.apa.org/pubinfo/answers.html
It's the American Psychological Association's FAQ about gay issues. Of course, some people will dismiss 40+ years of research into human sexuality as "biased," and that's their perogative, but I'm inclined to believe the preeminent psychological institution of the United States as an authority on the subject.
Here's a bullet point of note:
"What Causes a Person To Have a Particular Sexual Orientation?
There are numerous theories about the origins of a person's sexual orientation; most scientists today agree that sexual orientation is most likely the result of a complex interaction of environmental, cognitive and biological factors. In most people, sexual orientation is shaped at an early age. There is also considerable recent evidence to suggest that biology, including genetic or inborn hormonal factors, play a significant role in a person's sexuality. In summary, it is important to recognize that there are probably many reasons for a person's sexual orientation and the reasons may be different for different people.
Is Sexual Orientation a Choice?
No, human beings can not choose to be either gay or straight. Sexual orientation emerges for most people in early adolescence without any prior sexual experience. Although we can choose whether to act on our feelings, psychologists do not consider sexual orientation to be a conscious choice that can be voluntarily changed."
Food for thought, although I really didn't want this to be a big discussion on homosexuality.
Esprix