I don't accept that a man can be bisexual. I believe that heterosexuality and homosexuality lie at two ends of a continuum. Some people are more sexual than others but essentially they will fall into one camp or the other (forgive the pun). Those who are in the middle are probably more asexual than bisexual. I am at the far end of heterosexuality so that I even dislike men in a platonic or social context. Although this is as much to do with the drivel they talk about rather than anything sexual.
I don't know what David Walliams means by being 70% heterosexual. If he is 30% homosexual then he is gay, he cannot be both as the two are mutually exclusive. I would suggest he is eith confused, in denial or has 'gender issues'. My opinions are contraversial I know.
