Question: A segregation analysis of a large set of randomly selected families suggests weak evidence for a genetic influence on obesity. The investigators split their families into two groups, based on the median age of the probands. Results indicate a substantial genetic influence on obesity among the late-onset group of families, but no significant genetic influence on obesity among the early-onset group of families. You intend to map the genes (or gene) that influence(s) risk of obesity. Would you measure risk factors among family members? If so, which risk factors would you measure?