‘Jeopardy!’ champ Ken Jennings shares his knowledge

Clue: This brainiac earned 74 Jeopardy! wins as well as a spot on Barbara Walters’ list of the 10 most fascinating people of the year. Answer: Who is Ken Jennings?

The trivia mastermind and famed “Jeopardy!” champion is back in print with a new book that reveals parents may not know as much as they think they do. “Because I Said So!: The Truth Behind the Myths, Tales, and Warnings Every Generation Passes Down to Its Kids” humorously debunks such commonplace parental admonitions as “It’s too dark to read in here, you’ll hurt your eyes!” or “Don’t sit too close to the television. You’ll go blind!” and even “No soda! The sugar always makes you hyper!”

Armed with case histories, scientific finds and experiments on himself and his own children, Jennings let us in on what we really need to worry about ... and whether parents can now say “I told you so!”

What sparked your interest in trivia?

During the Trivial Pursuit boomlet of the mid-’80s, I was the perfect age to become one of those kids that’s always annoying people with random facts about jellyfish and George Washington’s dentures and the world’s biggest omelet and stuff like that. But I was already a huge game show nerd by that time. I would literally fake illness some days so I could skip school and watch “Family Feud.”

How did you become such an expert in cultural, historical and literary facts?

I think people assume that trivia geeks are constantly “studying,” like I read encyclopedias on the toilet. In fact, the know-it-alls I’ve met have all been that way since birth. They can just absorb information seemingly out of thin air. You know how it’s easy to remember facts about a subject you’re interested in? A favorite band or sports team or TV show or whatever? It’s the same for quiz kids, except they’re interested in pretty much everything. So “trivia expertise” is really just another way to say “curiosity about everything.”

What type of research or experiments did you do in order to prove or disprove the myths, tales and warnings you discuss in your book?

I was amazed by how many of these parental cliches had already been the subject of rigorous academic study. There are now good case-control experiments on everything from the “five-second rule” to knuckle-cracking to treating colds with chicken soup. In other cases, I had to talk to experts (plastic surgeons on the possible face-deforming effects of nose-picking, escalator-safety experts on the possibility of getting “sucked under” the comb plate, etc.) In a few cases, we even experimented at home. My kids enjoyed the “don’t shake up your soda can!” experiment much more than the “eating poinsettia leaves” experiment.

What is the history behind these myths, tales and warnings? If some of them have no truth behind them, how did they come about existing?

In most cases, you can see that the myths are just well-meant “err-on-the-side-of-caution” advice that overstates certain dangers. (Eating raw cookie dough, for example, can lead to salmonella, but a contaminated egg is a once-in-a-lifetime occurrence for most people.) But in other cases, I was able to pinpoint the original bad science that led to some parental adage getting passed down for generations. The thing moms say about 50% of your body heat escaping through your head? That’s a misinterpreted stat from a 1970 U.S. Army field manual. “Feed a cold, starve a fever” comes from the old humor-based theory of anatomy that was popular in medieval times. The underlying theory has been discredited for centuries, but the bad advice still sticks around somehow.

As a parent yourself, which warnings did you find yourself giving your children most often that you now know to be false?

I made the mistake of letting my 10-year-old son read an advance copy, and now nobody can tell him anything. My wife will say, “It’s too dark to read in there, turn on a light,” and he won’t even look up. “No, that’s not true, Mom. Any eyestrain will be temporary. It’s in Dad’s book.” So I’m not too popular in my own house at the moment.

Which warning were you most surprised to find out was false?

Apparently there are now at least a dozen good studies finding that sugar has nothing to do with hyperactive behavior in kids. I couldn’t believe it, but the science seems sound. It turns out that most of the times when kids fill up on sugar (holidays, birthday parties) also happen to be raucous occasions. And parents don’t want to hear the truth, of course, because “Hey, you’re the one who gave my kid all that soda” is a much easier thing to believe than “Wow, my kid was a holy terror at the birthday party.”

And which were you most surprised to find out was true?

People always sneer when Mom tells you to bundle up “so you don’t catch your death of cold.” Colds are caused by viruses, not weather, Mom! But there’s some new research out of Wales where subjects were more likely to catch cold after soaking their feet in cold water for half an hour. So chills might indeed make your body more susceptible to winter illness. Mom was right all along about wearing galoshes or going outside with wet hair.

Do you have plans to write another trivia book in the near future?

I just finished this trivia book about kids, and now I’m working on a trivia book for kids. I’m writing a series of “amazing facts” books for kids -- one about maps, one about Greek myths, one about U.S. presidents, that kind of thing. Exactly the kind of book I used to devour when I was 9 years old. I guess childhood obsession is destiny after all.

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