Your daughter has your hazel eyes and love of reading, and you passed your curly brown hair and sharp wit to your son.

A combination of nature and nurture develops children into unique individuals, but charming characteristics like dimples and freckles aren’t the only traits we can pass along to our offspring: research shows that children can inherit an extremely anxious temperament, which is a prominent risk factor for the later development of anxiety and depression.

A study at the University of Wisconsin-Madison showed how excess activity in three areas of the brain are inherited from generation to generation, and may increase the risk of anxiety and depression.

Researchers found that the brain circuit that was genetically correlated with individual differences in early-life anxiety involved three survival-related brain regions. These regions were located in the brain stem, the most primitive part of the brain; the amygdala, the limbic brain fear center; and the prefrontal cortex, which is responsible for higher-level reasoning and is fully developed only in humans and their primate cousins.

Dr. Andrew Fox, Dr. Ned Kalin, and their colleagues found that about 35 percent of variation in anxiety-like tendencies can be explained by family history.

Using this “genetic correlation” approach, the authors found the neural circuit where metabolism and anxious temperament are likely to share the same genetic basis.

Activity in the profrontal-limbic-midbrain circuit is probably involved in controlling the inborn risk for extreme anxiety that can be seen in early childhood.

“Over-activity of these three brain regions are inherited brain alterations that are directly linked to the later life risk to develop anxiety and depression,” says Kalin, chair of psychiatry at the UW School of Medicine and Public Health. “This is a big step in understanding the neural underpinnings of inherited anxiety and begins to give us more selective targets for treatment.”

“Basically, we think that to a certain extent, anxiety can provide an evolutionary advantage because it helps an individual recognize and avoid danger, but when the circuits are over-active, it becomes a problem and can result in anxiety and depressive disorders,” Kalin explained.

“Now that we know where to look, we can develop a better understanding of the molecular alterations that give rise to anxiety-related brain function,” said Kalin. “Our genes shape our brains to help make us who we are.”

Although this research doesn’t identify the exact genes responsible for anxious temperaments, it does help explain how genes affect brain function and can lead to extreme childhood anxiety.