This is not a Blimp. It's a sort of flying Queen Mary 2 that could change the way you think about air travel. It's the Aeroscraft, and when it's completed, it will ferry pampered passengers across continents and oceans as they stroll leisurely about the one-acre cabin or relax in their well-appointed staterooms.

Unlike its dirigible ancestors, the Aeroscraft is not lighter than air. Its 14 million cubic feet of helium hoist only two thirds of the craft's weight.

A pair of twins is born, and both infants begin to develop normally. By their first birthday, however, the male sibling has begun to diverge from his sister, showing less eye contact and affection. He often wears a spaced-out expression and fixates on certain puzzles and patterns. By age three, his mounting symptoms lead to a diagnosis that has become disturbingly routine in recent years: autism.

What causes the disease, which now strikes 1 in every 166 children, and why does it affect four times as many boys as girls?