Scan 1… were khakis from J. Crew, loafers and a grey sweater — a muted, non-assertive look. I wanted the examiner to trust me, to assess me as reliable and calm, maybe even a little dull, because my goal was to be granted free rein on the road with a 220 hp weapon of destruction at my disposal. I’d been driving for years, but that was on my American license and the English insurance company was starting to get huffy about my lack of proper credentials. As a result, decades after my first test in a New Jersey parking lot, I found myself taking a second exam under the flat wide skies of East Anglia. East Anglia! The Texas of the British Isles!

There was an enforced intimacy to the situation. I was alone in a car with the examiner, a paunchy male smelling of man sweat and breath mints. Our knees kept meeting across the phallic gear stick. It was like a very bad date, the kind you want to be over as soon as possible.

As it turned out, it was over quickly and the only reason I mention it now, eight years later, is because of a remark the examiner made at the end. We’d been out on the road for less than five minutes when he suddenly flicked his pen against his clipboard and said, We’re done. You passed.

Given I’d just reversed up over the curb, making the most tremendous grinding noise with the undercarriage, this surprised me. Really? I said.

Yes, really, he said. I’m not worried about you. You’re not what my job is about. My job’s about keeping as many 19 year-old boys off the road as I can.

Teenage boys are crazy, he said. They should all be locked up until they’re 26.

Those words came back to me, clear as a banner, a few days after the bombs went off in Boston and details began to emerge about the two boys, the Chechnya immigrants who seem to have been responsible for it. It happens I’ve been writing about immigrants and alienation and it struck me those confused and disengaged young men – the angry older brother, the biddable younger one –brought a significant and not often discussed element to the mix, namely, the raging hormones of the young male.

A boy is a mini-explosives’ factory. By the time he’s 16, he’s manufacturing androgens –most notably testosterone– by the truck load, 24 hours a day, seven days a week, producing all the raw materials required to shape aggression, strength and sex drive. It’s one of the miracles of chemistry, but the end product is a stroppy creature with shocking physical power, a rampant libido – and no control mechanism. A male’s frontal lobe – the bit of the brain tied in with regulating impulsive behaviour – doesn’t develop before he’s in his mid- to late twenties. Until then, he’s all revved up … with nowhere to go with all that fuel.  He’s the Incredible Hulk, expanding at a great rate, wanting to do something major and incapable of containing his rage.

Explosives’ factories have vents and outlets built into their design. Boys don’t.

Teenage girls are different. They don’t tend to act out. They act in. They stop eating. They start cutting. They shave their heads and pierce their bodies. In a sense, teenage girls are all about control — the result of the hormones they produce and the rate at which their brains develop.

But a young male – particularly a young male at a loss — is a self-generated bomb, and when I think of those two Chechnyan brothers and their pressure cookers from Target, I can’t help but remember an hysterical son in Newtown, Connecticut  shooting first graders with his mother’s Bushmaster rifle, and a pair of Goth outcasts with pump-action shotguns in a Colorado high school. I can picture them all together in a Law & Order-style line up and the question I end up asking myself is: Are they terrorists or hormonal boys with a grudge?