London ? Having trouble persuading your child to eat broccoli or spinach? You may have only yourself to blame.

According to a study of twins, food neophobia – or the fear of new foods – is mostly in the genes.

“Children could actually blame their mothers for this,” said Jane Wardle, director of the Health Behavior Unit at University College London, one of the authors of the study in this month’s American Journal of Clinical Nutrition.

Wardle and colleagues asked the parents of 5,390 pairs of identical and non-identical twins to complete a questionnaire on their children’s’ willingness to try new foods.

Identical twins, who share all genes, were much more likely to respond the same way to new foods than non-identical twins, who like other siblings only share about half their genes. Researchers concluded that genetics played a greater role in determining eating preferences than environment, since the twins lived in the same household.

Wardle said food preferences appear to be “as inheritable a physical characteristic as height.”

Unlike nearly every other phobia, neophobia is a normal stage of human development.

Scientists theorize that it was originally an evolutionary mechanism designed to protect children from accidentally eating dangerous things – like poisonous berries or mushrooms.

Neophobia typically kicks in at age 2 or 3, when children are newly mobile and capable of disappearing from their parents’ sight within seconds. Being unwilling to eat new things they stumble upon may turn out to be a lifesaver.

Still, experts say that the environment parents create is crucial to determining their children’s eating habits.

“It can’t all be genetics,” said Marcy Goldsmith, a nutrition and behavior specialist at Tufts University. “Parents need to offer their children new foods so they at least have a chance to try it.”