Neat timing for the first part of The Making of Me (24 July, 9pm), in which the actor and singer John Barrowman tried to discover what made him gay (in a series of three episodes in which, each week, a different celebrity goes on "a mission to discover the source of their defining trait"). Is it his nature, or did that time his parents made him wear a bikini while on board the QE2 do something odd to his brain? In Canterbury, the Anglican bishops have been working themselves up into the usual frenzy about homosexuality, one so shrilly indignant that you do wonder whether the so-called traditionalists grew up with as many Barbies in their closets as Barrowman did. (This was my favourite scene, when he examined the contents of his childhood toy cupboard: it wasn't the number of dolls that made me smile, so much as their delightful condition; while my Sindys had matted hair and sluttishly torn skirts, his Barbies were catwalk-fresh and accessorised to an unnerving degree.)
Then again, the nature v nurture debate has always seemed to me to be a red herring. How a person got gay doesn't change the fact that they are gay, nor should it make any difference to how they are treated by the rest of us. Barrowman himself was desperate to prove that his sexuality is innate and not learned, but I was never really clear why. The truth, I suspect, is that he and his producers felt the need to bring drama to the answering of a question that was basically rather uninteresting: why did this successful man, who had a happy if camp childhood, grow up to form a loving partnership with another man rather than a woman? It isn't as if Barrowman is full of self-loathing. You might as well ask why Cath Kidston grew up to love floral prints.
Barrowman is likeable and wholesome, and definitely a nice-looking sort of a chap, but he did not strike me as the brightest sequin in the drawer: there was a certain lack of reflection in his responses to the tests he underwent and a definite blankness in his eyes when talking to scientists, which he covered up with lots of squealing and flirting ("What a pleasant surprise!" he said, on shaking the hand of a particularly hunky gene researcher). This got pretty wearying after a while, and it meant that the tests themselves - brain scans, chromosomal analyses, psychological observations - existed in a vacuum: no one ever asked whether it is not in any way dangerous to go down this road of trying to pin everything on genetics.
Luckily, the results were inconclusive. Barrowman - surprise - got most turned on by pictures of man-on-man action, but performed more like a heterosexual woman when it came to skills such as map-reading and word association. Oh yes, and he knew all the words to Abba's "Chiquitita" as a teenager. On the other hand, his genetic make-up - the bottom tip of his X chromosome - matched that of his brother, who is straight. It seems that some 50 per cent of what makes a man gay occurs in the womb, but the jury is still out as to what that might be. After that, any number of factors may be at work.
Barrowman found all this frustrating - he clung to that 50 per cent figure like Barbara Windsor to a set of hot curlers - but to me, this news came as a relief. These things are complicated, and I relish it: such complexity is what it means to be human. Besides, by this point, I was obsessed with something else about Barrowman - something freaky that has nothing to do with his sexuality. In everyday life, he has an American accent. However, when he talks to his Scottish parents, a weird thing happens, and when I say weird, I mean seriously scary. It's as if his body is suddenly taken over by the personality of an East Kilbride market-stall holder called Shona. No one commented on this, but I was mighty troubled by it. I began to expect his stomach to be ripped open and for a monster resembling Jimmy Krankie to appear from within its bloody depths.
What's the science on this, I wonder? Is there a luvvie gene and, if so, what therapies may one day be available to treat it?
Pick of the week
27 July, 7pm, Channel 4
Robert Baer, ex-CIA man, on a cheap and terribly effective weapon.
House of Saddam
Starts 30 July, 9pm, BBC2
Drama about the inner workings of the Iraqi junta and first family.
Land of the Lost Jaguar
Starts 30 July, 8pm, BBC1
Scientists and cameramen visit Guyana's unspoilt jungles.