Scientific research has found that ＂one fat destroys three generations＂ may not be a joke.

　　Now you have more reason to pay attention to your waistline. A man’s weight seems to affect the activity of his sperm genes, which may be passed on to his children.

　　"Our results show that the environment will lead to changes in sperm cells, which may reflect the mechanism that obesity can be passed on to the next generation." Romain Barrès of the University of Copenhagen in Denmark said. He also believes that his findings may make some prospective parents seriously consider changing their behavior before pregnancy. We already know that children’s weight seems to have a great correlation with their parents. So far, many studies on the genetic mechanism of obesity mainly focus on mothers and their pre-pregnancy eating habits. But this new discovery shows that the father’s health is also very important.

　　After comparing the sperm of 13 thinner men and 10 moderately obese men, Barrès and his research team found that there was a significant difference in the epigenome of the sperm of the subjects (epigenome is a modified marker on DNA, which can affect gene activity). "We found that the epigenetic markers of about 9,000 genes in the sperm of obese men have changed." Barrès said.

　　"Now this result provides us with more evidence that our figure depends not only on our mother’s eating habits, but also on our father’s eating habits," said Susan Ozanne of Cambridge University.

　　In the past, it was thought that epigenetic changes would not be passed on from generation to generation, because the pattern of DNA methylation (an epigenetic change that makes gene activity lower) would be eliminated after fertilization.

　　However, a study earlier this year found that some genes seem to be able to escape this clearance. Moreover, there is evidence that short RNA fragments that determine which genes are methylated can be transmitted through sperm. Barrès’s research found that the level of some short-chain RNA in obese male sperm is relatively high, and the target of one RNA fragment is CART gene, a gene that controls appetite.

　　"We haven’t studied the transfer of these epigenetic modifications to future generations, but we are starting to do so," Barrès said. "We suspect that several epigenetic markers play a role at the same time after fertilization, which changes the procedure of embryo development.

　　But these epigenetic changes are not permanent. Barrès’s team analyzed the sperm epigenetic genomes of six obese men, all of whom underwent bariatric surgery to help them lose weight. It was found that after only one week, the methylation of 1,500 genes changed. A year later, the methylation of about 4000 genes changed.

　　But among them, only 2700 genes were identified by previous studies, and most of these genes did not match the pattern found in the thinner male group this time.

　　"I can only say that the change of epigenetic pattern caused by surgery can compensate obese patients to some extent," said Isabelle Mansuy of the University of Zurich.

　　But without comparison, we can’t rule out that this apparent heritage difference is due to the time span between the two tests, Barrès said.