Could your grandma's dining habits be influencing your genes? A new study in pregnant mice suggests they might.

The study found that a female mouse's diet while pregnant influences the genetics of not only her pups, but her pup's pups.

"This is a mouse model study, so it is not directly relevant to humans," cautioned study co-author Dr. David I. K. Martin, a researcher with the Children's Hospital Oakland Research Institute in Oakland, Calif. "However, what this study does tell us is that it is possible that not just the diet but other environmental agents that a mother is exposed to could affect not only the health of her child but also the health of her grandchildren."

"And this is the first study to nail down this kind of cross-generational effect on a specific gene," he added.

His team published its findings in this week's issue of Proceedings of the National Academy of Sciences.

Martin, who conducted his work alongside colleagues at the Victor Chang Cardiac Research institute in Sydney, Australia, focused on a strain of mice that possesses a specific gene involved in the determination of coat color, as well as obesity and the tendency to develop diabetes and cancer.

The authors point out that the mice -- known as Avy (or "viable yellow agouti") mice -- are as genetically identical to one another as identical twins would be. This enables scientists to more easily isolate and compare genetic behavioral differences that could result from exposing the mice to a wide range of dietary factors.

In this instance, the researchers offered some female Avy mice a standard lab diet throughout their pregnancy. The diet contained foods typically consumed by humans.

A second pool of mice was offered additional supplementation for one week in the middle of their pregnancy. Supplements included folate, choline, betaine, vitamin B12, zinc, and methionine.

At birth, pups' coat color was assessed in terms of shades of yellow and brown. The scientists used these as markers for specific gene activities.

Mice exposed to the supplements in utero had browner coats, the researchers found.

Subsequent breeding of females from this "first generation" of brown-coated mice revealed a carry-over affect to the next generation. Despite this time consuming a supplement-free diet throughout their pregnancy, these grandchildren of the original mouse were also born with similarly brown coats.

Having identified a clear effect of diet on the gene behavior of two generations of mice, Martin and his colleagues said they're not yet sure how far downstream such environmental influences might go.

"This could go in humans for decades," Martin postulated, "because the generation time in humans is now about 30 years. So, 100 years from now -- when a grandchild is 70 years old -- society could still be dealing with the effects that stem from a mother who is pregnant now and is exposed to something that affects the fetus."

Dr. Marcus Pembrey, an emeritus professor of pediatric genetics with the Institute of Child Health at University College London, said the findings weren't all that surprising.

"We've published evidence of similar trans-generational effects in humans, but not with this same gene," he said. "So this is a further piece of evidence that changes in nutrition can affect the activity of genes in descendants as well as in the fetus being exposed."

Martin stressed that the current work in mice is not proof that similar long-term dietary effects are at play in humans.

"It's really not possible to do this kind of research with humans, because we can't do experimental manipulations of this kind among people," he said. "So, it would not be responsible to prescribe that anyone take any course of action based on this study."

Pembrey agreed. "It would be very important to say that we are a long way off from interpreting these mouse findings in relation to humans," he said. "Yes, this trans-generational effect has been observed in people, but as yet we do not know what the molecular mechanism is -- let alone which genes are involved."

"What I could advise is to eat a healthy diet," offered Martin. "But I would not advise that anyone run out to take vitamins, or not to take vitamins, based on this work.