What shapes us the most — Is it nature or nurture, genes or our environment? People have been asking this question in one form or another for centuries. While there is still no simple answer that satisfies everyone, researchers have recently gotten a little closer to it.

Take the question of how much we are shaped by our families as opposed to our neighborhoods.

Both can strongly affect a person's health and life. Living in a neighborhood near green spaces, such as parks, can boost a woman's chance of having a healthy baby. And the social environment of a neighborhood — whether we feel it's risky or close-knit — affects heart health.

Of course, the goal is to help prevent mental illness, not to cause it. Perhaps the study results help show a way.

Families matter, too, of course. Parents are key to making sure teens get the sleep they need. And on a less positive note, family conflict increases the risk of premature death.

So which matters most, family or neighborhood? Can this even be measured?

A study of over half a million Swedish children says that when it comes to the mental health of children, family (including a person's genetic makeup) is six to eight times more important than the neighborhood kids are living in.

The study did not prove that a characteristic of a family or neighborhood poverty caused a psychiatric disorder. What it found over an 11-year period was how often children living under these conditions developed a psychiatric disorder such as depression, conduct disorder or ADD. The researchers were also able to estimate statistically the overall contributions family and neighborhood characteristics each made to the rate of psychiatric disorders.

During the course of the study, over 26,000 children (4.8%) developed a psychiatric disorder. Family characteristics were about six and a half times as likely to be responsible for internalizing disorders — such as anxiety and mood disorders like depression — as neighborhood characteristics were. For externalizing disorders such as conduct disorder, family characteristics were almost eight times as likely to be responsible as neighborhood characteristics.

The strongest family risk factors were having parents who weren't married, parents with little education, and low family income. Compared with boys, girls were twice as likely to develop internalizing disorders but were less than half as likely to develop externalizing disorders.

While the results clearly show the strong link of family to the development of psychiatric disorders, it doesn't mean that the role of neighborhood can be ignored. Living in a highly deprived neighborhood doubled a child's risk of developing conduct disorder during the course of the study. Both neighborhood and family matter — a lot. But it seems that family matters more.

Of course, the goal is to help prevent mental illness, not to cause it. Perhaps the study results help show a way. After all, it's usually easier to make changes in a single household than to make them in an entire neighborhood.

The study appears in the Journal of Psychiatric Research.