When wondering whether genes are contributing to your struggle with weight, a new study suggests it might be useful to look within — at the garden of bacteria growing in your gut.

In particular, you might well wonder whether, in addition to their failure to bequeath you the genes for athletic prowess and a strong jaw line, your parents also failed to pass on a genetic predisposition to play host to the bacterium Christensenella minuta in abundance. In a new study that explored the fecal samples of 416 twin pairs in the United Kingdom, researchers found evidence to suggest that this strongly heritable strain of gut bacterium protects against obesity.

The new research, which draws a line between genes and obesity that passes through the garden of intestinal bacteria, was published in the journal Cell. The research was led by Julia K. Goodrich and Ruth E. Ley of Cornell University's Department of Molecular Biology and Genetics.

Nobody would deny that parents' girth exerts a powerful influence on their children's propensity to becoming overweight or obese. But how much of that is nature — genetics — and how much is nurture — family consumption patterns and preferences — has become a subject of highly active research.

The British twin study suggested that genes play a key role in whether an individual will host several strains of bacteria — including C. minuta — in abundance. And it found that levels of bacteria in the Bacteroides family seem to be influenced more by environment than by genes. But they also said fecal transplants are showing promise as the beginning of a lengthy effort that may help identify ways to combat obesity.

Los Angeles Times