The idea that experience and genetics are unrelated is being challenged by an increasing number of scientific studies, reports The New York Times. These recent study results reveal the possibility that human experience can actually alter gene expression in sperm and, ultimately, our offspring.

One example is evidenced in recent research by a team of Rockefeller University, who conducted a study that found that stressed rats possessed an unusual level of epigenetic microRNA molecules. Furthermore, when they injected thee microRNAs into the embryos of rats that came from mellow fathers, they noticed that the offspring developed rats with altered stress responses.

Another study from the University of Copenhagen (UoC)  found that male rats fed a high-fat diet tended to father offspring that had an increased tendency to gain weight, higher fat development and a decreased ability to regulate insulin levels.

In order to explore the possibility of similar results in humans, Romain Barres, who headed the UoC study, collected sperm from 10 obese and 13 lean Danish men and then examined their epigenetic differences. The key difference came down to methylation of their molecular caps.

Using the different profiles between the two groups of men, they compared their genetic methylation patterns after bariatric surgery to see if losing weight altered them. As reported on Thursday in the Cell Metabolism journal, they discovered that a year later, over 3,900 of the genes exhibited altered methylation patterns.

"I don't want to speculate whether it's positive or negative in the following generation," said Barres, who is now expanding on the results and exploring blood patterns as well. "We're going to try to see if there's something transmitted all the way down."