Why is it that one person may tend to gain weight, even if he eats no more and exercises no less than a slim friend? Recent studies suggest that the factors that control metabolism may depend on your genetic makeup. One study involved 11 pairs of identical twins fed about 1000 calories per day more than needed to maintain initial weight. Activities were kept constant, and exercise was minimal. At the end of 100 days, the changes in body weight (in kilograms) were recorded for the 22 twins.16 Is there a significant positive correlation between the changes in body weight for the twins? Can you conclude that this similarity is caused by genetic similarities? Explain.

Pair Twin A Twin B 4.2 7.3 6.5 5.7 7.0 7.2 5 7.8 7.9 6.4 8.2 6.5 8.2 6.0 10 11.2 13.7 13.0 11.0 5.5 7.1 8.2 9.1 9 11.5