Scientists have little doubt that genes can affect a child's behavior, but exactly how nature and nurture work together is still somewhat of a mystery. One recent study concluded that almost all psychological traits are at least somewhat genetic. Research has also shown that twins often have similar personalities even when they have been raised apart. "When parents say, 'My child has my hot temper,' there is definitely an element of truth to that," says Greg Carey, PhD, associate professor at the Institute for Behavioral Genetics at the University of Colorado, Boulder.
The resemblances can be uncanny. Amber Carlsen, of Salt Lake City, says her 2-year-old daughter, Haylee, is a deja vu version of herself as a child -- bossy, independent, and fastidious. "I'll ask my mother to watch Haylee in the tub for a minute and then come back to find Mom laughing," says Carlsen. "She'll say, 'Haylee's so much like you were, it's just amazing.'" One day, Haylee came home from the babysitter's house all excited about Strawberry Shortcake characters -- and she's been a huge fan ever since. "It stopped me dead in my tracks because I loved those pink dolls when I was a kid but have never introduced them to Haylee," says Carlsen.
"There's no Strawberry Shortcake gene," says Dr. Carey, "but genetics can certainly shape preferences for things like color, which could lead a child to make choices that are similar to a parent's." Even favorite foods may be partly rooted in biology. One recent study found that kids who have a taste gene that's associated with a sensitivity to bitterness are less likely to pick milk or water as their favorite drink and more likely to love sugary soft drinks and cereals.