Some people believe that by telling their children about homosexuality, they might start 'experimenting' because they never knew they could be gay before. It's a form of bigotry born of ignorance; what they forget that is that kids aren't suddenly going to try and be gay because they were told about it - rather, kids that are gay, once they get to the age where they start to mature sexually, are going to know that not only are some people attracted to their own sex rather than the opposite, but also that it's completely OK to be attracted to their own gender. They weren't 'turned gay', they simply exhibited behaviour that was always going to appear, education or not. The difference is that with education, homosexual adolescents can grow up feeling more secure that society at large accepts their presence and chosen partners.
The Guardian did an interview with David Davies a few weeks ago, a British Conservative politician who caused controversy after making remarks against the drive for gay marriage in this country. The most interesting thing about the interview is that, while Davies genuinely doesn't want to offend anyone, he comes out with some shockingly homophobic remarks simply because he didn't know any other situation. It's quite the insight, and is certainly food for thought as to how many overtly homophobic people are genuinely intolerant, and how many are simply lacking in education as a result of a heteronormative society:
http://www.guardian.co.uk/politics/2012/dec/21/david-davies-gay-marriage-interview