Why won't your kid eat his veggies?

Don't blame your kids the next time they say "Yuck!" to broccoli -- it might be your fault.

New research suggests food fussiness is just as heritable as height and weight, about three times more influenced by genes than by environment.

The new study of more than 5,000 pairs of twins, published in The American Journal of Clinical Nutrition, measured each child's level of food neophobia, the scientific term for the fear of new foods. While infants willingly accept whatever food comes their way, toddlers (ages 2 to 5) are much more resistant to unfamiliar cuisine.

"Parents can take comfort in the fact that a lot of this is beyond their control," says Lucy Cooke, the study's lead author and a researcher at University College London. "It's not their fault or bad parenting that causes pickiness. But it's something that can be changed with strategies."

The best way to reduce the problem, psychologists say, is by repeatedly introducing the rejected food to your child. Commitment is key: it usually takes between 10 and 15 introductions exposing the taste buds to asparagus or Brussels sprouts before they accept the new flavors.

Since nature favors traits that are adaptive, what is it about pickiness that makes it inherited? Some psychologists think it might have evolved as a defense mechanism, to protect us from poisonous foods.

"In nature, most things potentially edible are also potentially toxic," says Paul Rozin, a psychology professor at the University of Pennsylvania. "When you're a child, you don't know ahead of time which ones are toxic."

But will the excuse work at the dinner table? That depends on a parent's taste.