Why do scientists still debate about nature and nurture?

If scientists agree it's not nature versus nurture; rather, it's the interaction of nature and nurture, why does a debate still exist?

In 2003, scientists published a groundbreaking study on the interaction of nature and nurture, showing how a particular gene and exposure to stressful life events (like losing a spouse or being fired from a job) combine to contribute to the risk of developing depression. The study was hailed in media outlets around the world as an example of moving beyond the old "nature versus nurture" debate and instead revealing how something as complex as depression arises from the interaction of nature and nurture.

In the years that followed, dozens of international teams of scientists set out to replicate that original 2003 study to see if they could find the same interaction of nature and nurture. Many of those studies came back positive, confirming the original study, but many also came back negative, negating the interaction.

"Now, in 2014, the scientists who study the nature and nurture of depression can't agree," said James Tabery, historian and philosopher at the University of Utah. "They argue at scientific conferences, in journal editorials and in news reports covering the controversy. How can scientists from all over the world look at the same data and results but then reach such different conclusions?"

According to Tabery's new book, "Beyond Versus: The Struggle to Understand the Interaction of Nature and Nurture," scientists can't agree because they're not just arguing about data and results. Rather, they're engaged in a fundamentally philosophical debate about what "the interaction of nature and nurture" actually means.

Tabery explains how scientists throughout the 20th and now 21st centuries conceived of the interaction of nature and nurture in two radically different ways—one side envisioning it as crucially important and the other side dismissing it as a rare nuisance.

"From disputes in the 1930s regarding eugenic sterilizations, to controversies in the 1970s about the gap in IQ scores for black and white Americans, to the contemporary debate about the causes of depression—the book traces the frustratingly persistent debate that keeps emerging, even as the cast and context of each iteration of that debate changes from decade to decade," added Tabery.

The result is a book that tells the story of the past, takes stock of the present and envisions the future of a science that continues to make headlines and raises controversy.