Less than two years ago, scientists officially linked processed foods to autoimmune disease and the consequences may ripple to future generations.
Medical researchers have before shown a link between a father's weight and diet at the time of conception and an increased risk of diabetes in his offspring.
In research conducted on mice, a team from the Chinese Academy of Sciences found that unhealthy eating behaviours were recorded in a tiny molecule that could then be transmitted through sperm to the embryo.
"It's another critical piece of information that says we really need to start looking at fathers' pre-conception health," says Sarah Kimmins, McGill University.
This tsRNA molecule, which is caused by a parent who grows obese from a diet of fatty food, could cause offspring to be inclined to consume substantial levels of glucose. It could also lead to other disorders such as an insensitivity to insulin.
The CAS study, published in the journal Science, backs up similar findings by researchers at the University of Massachusetts Medical School. Both studies have revealed worrying implications for parents living in especially unhealthy environments.
However, both research papers contradict the widely accepted hypothesis that human genes are constantly mutating. The Chinese study, led by Duan Enkui, has instead suggested that they are subject to the changing behaviour of an individual.
There are two main kinds of evidence that have shown that men's (and other male mammals') environment before conception affects their offsprings' health:
- Epidemiological studies that link things such as a father's smoking and diet with their children's and grandchildren's health, growth and risk of health problems such as cardiovascular disease.
- Lab studies in animals making a direct link between a father's diet, stress and exposure to drugs or toxic substances with their offsprings' health.
"Our study shows that trait inheritance can be achieved by RNA alone, which takes us into a totally uncharted area," Professor Duan said.
He added that his findings supported claims by nineteenth-century French biologist that certain forms of behaviour will bring a competitive advantage that can help a creature better adapt to its environment.
"In the fields of infant nutrition, diabetes, obesity, and the metabolic syndrome, the term "metabolic programming" has been coined to give a name to the observation that environmental experiences early in life may be "genomically" remembered and give rise to health outcomes manifesting later in life. Epigenetics emerges as an important mechanism underlying this phenomenon," concluded researchers.
Further research is needed before Duan's radical findings become widely accepted by the scientific community, said Meng Anming, a molecular biologist at Tsinghua University in Beijing.
Speaking to the South China Morning Post, Meng said the studies had found a different way in which traits might be inherited, but the evidence so far was not strong enough to challenge the dominant role of DNA and Darwin's theory of natural selection, which dictates that nature alone decides which traits or species are the fittest to survive.
"The effect of the RNA [molecules] may be limited to a certain number of generations," said Meng. "They are side-kicks in comparison to DNA's dominant and long-lasting role."