The Shadow Genome: Why DNA Isn't Destiny

How does a mother’s weight-loss surgery affect her child’s risk of obesity? It’s a question scientists have been struggling with since a Laval University study published in April, which looked at children born to mothers who’d undergone gastric bypass surgery prior to their pregnancy. Researchers knew the children were less prone to obesity, but as they tried to figure out why, they found something unexpected. The children’s genes were different — not their genetic code itself, but the markers in between that code. It was a small study, but the results were striking: more than 5,000 genes were expressed differently when parents had undergone the surgery. The surgery had changed something in the mother’s DNA, and when the children were born just a few years later, it appeared to have changed in them too.

The finding is part of a raft of studies looking at the phenomenon of epigenetic inheritance — how characteristics can be passed down from parent to child without ever touching the genetic code. Together, these studies are having a profound impact on how scientists look...