http://www.usatoday.com/news/opinion/forum/2011-05-31-Genetics-drives-obesity_n.htm
"The role of genetics
However, surprisingly, data from adopted twin studies indicate that in the United States, about 80% of the variation in body weight is determined by genes. Again, that's about the same degree of heritability as a characteristic such as height, and much greater than that for other conditions that we now clearly regard as running in families, including breast cancer, schizophrenia and heart disease. Yet, we don't typically call a heart disease sufferer a weak-willed loser."
http://online.wsj.com/article/0,,SB110117970881981681-search,00.html?collection=wsjie%2F30day&vql_string=cdc%3Cin%3E%28article-body%29
"According to the Journal, a CDC document "concluded that the mathematical errors may have inflated the study's death toll by about 80,000 fatalities, or 20% of the total deaths."