Which of the following statements does NOT support the research evidence for genetic factors?

a. There is a greater relationship between children and their adoptive parents, as compared to their biological parents, when considering morbid obesity.
b. Genetic heritability of obesity approximates 25-40 percent.
c. The 'thrifty gene' is a term scientists have coined to indicate an increased energy efficiency in the obese to conserve energy.
d. A predisposition to sweet, high-fat foods, impaired hormonal functions, and a smaller percentage of slow twitch muscle fibers have all been implicated in the development of obesity.