Unfortunately, modern life has too many environmental variables to catalog: cell phones, air travel, televisions, vitamin pills, food additives. Many people believe that environmental heavy metals have afflicted their children. Others blame a broad range of other substances, especially bisphenol-A, a man-made, estrogen-based polymer used in plastics, which has an annual production of more than three million tons. Most geneticists acknowledge that these questions have not been fully resolved, and that they may not be resolved for many years.
