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?

When mosquitoes brought West Nile virus to New York, all the papers said it was going to be the next big deadly epidemic (which, of course, it wasn’t). The day the news came out, I was in my garden in Pittsburgh, and a mosquito landed on my arm. I smacked it, then immediately thought, “Oh my god! West Nile virus!” So I ran inside and did something I hadn’t done since grade-school summer camp: I doused myself with insect repellant. Then I got a whiff of the fumes and remembered I just read an article saying insecticides cause Parkinson’s disease!

In our March feature story, Sally Has 2 Mommies + 1 Daddy, life sciences associate editor Rebecca Skloot noted that each year, thousands of women expose themselves and their future children to fertility treatments . Yet most of these treatments have not been tested for safety, and are not subject to regulation. These technologies—like in vitro fertilization (IVF) and the method used for injecting sperm into eggs—have now been connected to a risk of serious birth defects.