Poor nutrition can have an effect on children through a father's sperm, research suggests.
Mouse studies showed that a male parent's eating habits may alter the metabolism of offspring that he has never met.
Scientists still do not know how the mechanism works, but believe some kind of nutritional signal must be carried through sperm to shape early development.
The findings lend support to the theory that environmental factors can trigger heritable genetic effects. Evidence for "epigenetic" influence has already been seen in a number of studies.
The most striking human research from Sweden suggested that a grandfather's poor diet increased the risk of diabetes, obesity and heart disease in second-generation children.
In the new research, scientists focused on the genes in mice whose fathers were fed a low-protein diet. They found that hundreds of genes were altered in offspring sired by the protein-starved males.