And it's all because your grandparents were exposed to DDT.
Obesity stems primarily from the overconsumption of food paired with insufficient exercise. But this elementary formula cannot explain how quickly the obesity epidemic has spread globally in the past several decades nor why more than one third of adults in the U.S. are now obese. Many researchers believe that a more complex mix of environmental exposures, lifestyle, genetics and the microbiome's makeup help explain that phenomenon. And a growing body of work suggests that exposure to certain chemicals--found in nature as well as industry--may play an essential role by driving the body to produce and store surplus fat in its tissues. Evidence of that cause-and-effect relationship in humans is still limited, but in laboratory animals and in petri dishes data linking the chemicals to problematic weight gain are mounting. Moreover, the effects in animals appear to be passed on not just to immediate offspring but also grandchildren and great-grandchildren--potentially [emphasis mine] accounting for some multigenerational obesity.
Scientists already know that humans are exposed to a potent soup of chemicals even before birth. Some of those chemicals, known as endocrine disruptors, may shut off, turn on or modify signals that hormones produced by the body would otherwise carry. That disruption appears to short-circuit regulation of energy levels and how the body reacts to stress, sometimes with disastrous consequences. Hundreds of contaminants typically found in consumer products, including dozens of flame retardants, numerous pesticides and endocrine disrupting bisphenol A, have been detected in the umbilical cord blood of newborn babies--which means that "to a disturbing extent, babies are born 'pre-polluted,'" according to the President's Cancer Panel.
The presence of these chemicals in the womb, in itself, does not mean they will cause any harm. Animal research, however, suggests that many of these substances may cause serious, long-term consequences. For example, tributyltin, an endocrine disruptor found in water pipes and used in plastics, increases fat mass, reprograms stem cells and produces more fat cells in mice across multiple generations, according to a study published in 2013. Meanwhile, when pregnant rats were exposed to pollutants including common plastics, agricultural chemicals and jet fuel, their great-grandchildren were more likely to be obese or have other disorders, according to research from Washington State University biologist Michael Skinner. As Skinner noted in the August Scientific American, "Some part of the increases in obesity, diabetes and other fast-rising diseases among baby boomers and more recent generations might have originated with their parents' and grandparents' exposure to pollutants such as DDT and dioxin." Some of this trend may be due to alterations that occur in sex cell DNA that are then passed on through affected sperm but more studies need to firm up that relationship.
Researchers need to discover some endocrine un-disruptors so that we can turn on the de-activated gene expressions and pass that on to our offspring.
That would be a fantastic idea...I wonder if there's a way to introduce heavy metals removal from our bodies, as well.