A new report published in the journal Child Development suggests that there might be more of a connection between parental stress and how it effects children than they once thought. The study examined cheek cell DNA from 109 adolescents. It then compared the results to the data from University of Wisconsin researchers who had studied the parents' stress levels between 1990 and 1991 when the children were infants. It found that a chemical reaction called methlyation was more prevalent in the DNA of children whose parents reported high levels of stress when they were young. “Methylation acts like a light dimmer for genes. Each gene can be totally turned off, or totally turned on, or anywhere in between,” said Clyde Hertzman, director of UBC-based Human Early Learning Partnership and an author of the study. The good news is that the DNA found to be associated with this study does not affect a child's behavior or reaction to “external stress.” Dr. Marilyn Essex, a professor of psychiatry at the UW School of Medicine and Public Health, told the Star Tribune that this is groundbreaking news “because we’ve shown that day-to-day stress in early childhood can predict changes in DNA that can be observed in adolescence,” said Essex. “It’s further proof of the importance of those early years and the lasting effects of children’s family environments during infancy and preschool.” Added Hertzman: “In the past, your DNA was seen as a blueprint. It had a one-way conversation with the world. In fact, it's a twoway conversation and the environment is telling it how to behave.” The study also showed that while a mother's stress level during infancy affected children more than her stress level during the preschool years, the reverse was true for fathers. It also found that the stress levels of the father somehow had a greater effect on the daughters, while the mother's stress level affected both sons and daughters.