Most of what parents pass down to their children biologically is passed down through DNA. DNA in the egg and sperm make up a biological blueprint that influences traits from eye color to cancer risk.

But eggs and sperm contain more than just DNA, and some of the other molecules they carry can also influence the health of the next generation. University of Utah Health researchers are uncovering how small molecules in sperm can carry the health consequences of eating poorly to the next generation.

They’ve found that when male mice eat a high-fat diet before conception, their offspring have a higher risk of diabetes-like health conditions. By analyzing the male mice’s sperm, the scientists discovered that mice that eat unhealthy have higher levels of particular kinds of molecules called small RNAs.

To figure out whether the small RNAs were directly responsible for the offspring’s poor health, the researchers extracted them from sperm and then added the small molecules directly to a developing mouse. Sure enough, mice that had been injected with the sperm RNAs had a higher risk of poor health.

These discoveries were only made possible by working with animals. Scientists could ensure that the mice ate a specific diet, and because mice breed rapidly, the researchers could see health effects in the next generation within a reasonable time span. Mice and people experience similar health changes when they eat a high-fat diet, which means that working with mice lets researchers better understand how diet affects the health of parents and their future children.

New findings indeed suggest that the results that Chen’s lab found in mice also apply to people. Fathers with obesity or who are overweight tend to have specific kinds of small RNAs in their sperm, and their kids have a higher risk of early-onset obesity and reduced metabolic health.

The good news is that while changing DNA requires gene-editing technology, small RNAs are much more malleable and likely changed by improved health behaviors. In mice, returning to a healthy diet rapidly restored sperm RNAs to normal. Eating healthy likely provides similar benefits for people. And in the future, scientists may be able to develop treatments that directly target small RNAs in sperm to reduce a future child’s risk of metabolic disorders.

This sentence might read better without the dashes — but wanted to flag it in case you felt it was necessary to set “biologically” off.