Transgenerational epigenetics has shown that exposure to a toxin can cause illness in future generations. Some studies show the effect on obesity. Women who were exposed to certain toxins had children at greater risk of obesity. One study suggested that the effect could be passed down for up to 12 generations. Exposure to DES (the synthetic estrogen diethylstilbestrol) can epigenetically cause a greatly increased risk of developing reproductive tumors in future generations.