Iraqi children run to welcome British Troops from 42 Commando as they go on patrol in the Southern Iraqi town of Umm Qasr, 22 miles south of Basra, Thursday March 27, 2003.

Childhood is the happiest, most carefree of times. That is, unless your country has been torn apart by war.

The United Nations estimates that children in 50 countries are currently growing up in the midst of war or its ugly aftermath. In the past decades, 2 million children have been killed and 6 million injured in war-torn places. And 23 million children have been forced from their homes.

Most kids live through the brutality of war, but even those who do come out the other side with a whole new moral outlook.

Roberto Posada and Cecilia Wainryb of the University of Utah were concerned about the fact that "more and more of the world’s children are being sucked into a bleak moral vacuum — a psychological space devoid of basic human rights and values," and they wondered how those children would develop a sense of right and wrong given the bleak condition of their lives.

And so they decided to ask the kids. Colombian children were appropriate subjects for Posada and Wainryb's question because Colombia has been engaged in civil war for 50 years; children in that country have been exposed to homicide, theft and physical violence on a daily basis. They gathered 96 children and adolescents who had been displaced from their homes and were currently living in poverty, most of them without parents, and questioned them about the morality of stealing or harming someone.

Surprisingly, these very damaged kids all said that stealing and harming others was wrong, morally wrong, even if everybody did it. Their ability to hold on to what is right and wrong speaks to the very depth of a moral character that is universal in all humans, no matter what happens. And this makes sense — social animals such as humans must share some common rules to make a society function, and even in anarchy, those rules hold.

But the researchers also found that the children had a very different view of right and wrong within the context of revenge. Most of the kids didn’t think it was so bad to steal or harm if the idea was to get back at someone.

That moral frame shift is not just discouraging, it also speaks to the roots of most human conflict. Fights, terrorism and all-out conflict are often based in real or imagined scenarios where each side complains they have been ripped off or harmed.

And then comes the justification of revenge. You take something of mine, I have the right to take something of yours. You have harmed me or those I love, so I can righteously harm you and yours.

People may be naturally moral and instinctively know right from wrong, but set into the social context of tit-for-tat, all notions of good and bad go out the window. Revenge is also so much part of our make-up that it, too, must have some deep moral value, albeit a twisted one, that works for human societies. We project our own. We hurt for them, we steal for them, we are together, no matter what, which probably helps our genes survive.

No one should be surprised if those Colombian kids grow up and continue in the violence of war. They have, after all, been dragged into the complex network of revenge justice, a system that by its very nature is handed down from generation to generation.

Meredith F. Small is an anthropologist at Cornell University. She is also the author of "Our Babies, Ourselves; How Biology and Culture Shape the Way We Parent" (link) and "The Culture of Our Discontent; Beyond the Medical Model of Mental Illness" (link).