For as long as he has been aware of his sexuality, Torchwood's John Barrowman has been convinced that he was born gay. As John battles with a battery of brain tests designed to see how straight and gay brains differ, can scientists prove his theory that a person's sexuality isn't a choice? Interesting clip from the BBC science series Making of Me. Watch more high quality videos on the new BBC Worldwide YouTube channel here: http://www.youtube.com/bbcworldwide