But it's not just exposure to poverty than can alter DNA for generations to come.
Exposure to tobacco does it, as does exposure to violence and the stress that comes with it.
Researchers with the Traumatic Stress Studies Division at the Mount Sinai Medical Centre in New York City conducted a study to see how the violence and stress of 9/11 would affect the children of the estimated 1,700 pregnant women who were directly exposed to the World Trade Center attacks.
Shortly after the attacks, researchers at Mount Sinai studied 38 pregnant women who were at or near the World Trade Center on 9/11, some of whom had developed PTSD.
They took samples of saliva from the women, and measured the levels of cortisol, a stress hormone, in their bodies. Higher levels of cortisol in the body mean more stress, and vice versa.
The researchers found that the women with PTSD had significantly lower levels of cortisol in their saliva than women who were exposed to the attacks, but who did not develop PTSD.
Around a year later, the researchers measured the levels of cortisol in the newborn children, and found that those born to mothers who had PTSD as a result of 9/11 had lower levels, than those born to mothers who were PTSD-free.
Basically, the researchers found that the children born of moms who were traumatized by the events of 9/11 were literally living with the results of their mothers' pain and trauma.
So, not only can our life experiences alter our genetic make-up, they can alter the genetic make-up of our offspring, and, as some studies have shown, even our grandchildren and great-grandchildren.
Think about that.
Because of epigenetics, whenever there's war, violence, poverty, famine or just about any other stressful situation, not only are our bodies changing, but those of future generations will, too.
That's why it's so important that we do everything possible to protect future generations by making the world work well today.
For example, we must confront America's racism and poverty epidemics head-on and start building a larger and more inclusive middle class, so that communities like Ferguson can leave the stress of poverty behind.
At the same time, we need to be creating a safer world, free of major stressors like wars, violence, and militarized police occupations.
Basically, we need to be working towards a more nurturing society.
According to the American Psychological Association, one-third of Americans suffer from extreme stress, whether it's from exposure to traumatic events like 9/11, or exposure to a life of poverty.
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