I hope you realize that that's not actually how sexuality works. It isn't a series of boxes that you climb into so that you can have an identity. It's a spectrum. It's in flux. It's wonky. At no point in time are you ever a point stuck in stasis. You're moving and being moved as you are affected. That's how sexuality works.
So making a statement like, "Most of the population is born straight," has no basis whatsoever, especially since so many people are now coming out of the closet (celebrities included, making for queer role models and opportunities to want to come out now that you've seen queernees associated with some sense of positivity). It's just that straight is normative in society, and therefore is the one thing that's plastered on billboards, on television, in magazines, all over the media, and is therefore the only thing that is either talked about or primary in the public consciousness. Hence believe there are "more straight people," when really that makes no sense at all.
Of course it could work quite well, regardless of which permutation you pick (curious people, actually queer people, one curious person and one queer person, etc.). We've had the potential for a queer coupling in David and Darren, but that lasted for about twenty-four seconds until we quickly realized that it was more likely that Darren just wanted to cling to someone popular in order to ride to the final days. This could be refreshing. And Big Brother desperately needs something refreshing or it won't last past next year. That's not to say that this would be the thing to save Big Brother - it has a lot of kinks to work out. But it could be one part of a larger strategy to do new things and take risks that normally would not be taken for the sake of security, and in this case security is no longer translating to ratings - people want to be challenged when they watch, otherwise they fall into monotony and it's no longer interesting.