Well, firstly you might explain exactly what you mean by “100% heterosexual.” The idea that you can place sexual orientation on some sort of sliding scale presupposes an objective measure of what constitutes “100% heterosexuality” and “100% homosexuality.” I just don’t think we have such a yardstick.
For example, would you consider me 100% heterosexual if i told you that i look at straight porn and have only ever had sex with women?
What if i then told you that i had some gay male friends, and that we sometimes kiss each other on the lips instead of shaking hands as a greeting? I have no desire to have a sexual relationship with these guys. To be honest, the idea of fucking a guy kind of grosses me out. But i also have no problem kissing one as a greeting, and i don’t feel that doing so makes me less “heterosexual” than i might otherwise be.
And this leads to the whole question of whether ones sexuality is determined purely by who one’s sexual partners are. There are guys, for example, who fuck other guys yet who self-identify as straight. And this is by no means a new phenomenon–it’s been going on for ages. For a discussion of how this sort of thing played out in relatively recent history, i highly recommend the book Gay New York by George Chauncey. A very recent manifestation of this type of thing is the so-called “down low,” a term used to describe (usually African-American) men who are married and consider themselves straight, but who seek out other “straight” men for sex.
And what about the inverse–someone who has a close emotional attachment to someone of the same sex, but who doesn’t have sex with that person? Is physical contact required in order to determine someone’s sexuality? And if so, are people who remain llifelong celibates then, by definition, without sexuality?
And what if you have sex for money? If the magazines and the gossip is to be believed, many of the male actors who make money doing gay porn consider themselves “straight.” Where would you put them on your scale?
In short, the variables and the multiplicity of possible definitions make a project such as your inherently problematic. And even if they didn’t, i think a more important question is: Why does it matter? Why do we need to place people on a scale or in a box, especially over an issue that is, essentially, no-one else’s business?