Genetics,Causes of Obesity

Genetics clearly play a role in obesity. It has been noted that an
adopted child’s body weight is usually more similar to the body
weight of his or her biological parents than that of his or her
adopted parents. Identical twins usually have similar occurrences
of obesity. Studies have also shown that fraternal twins
do not show this same likelihood of obesity; when one twin is
overweight, the other is very often not. These examples help
demonstrate that genetics play a significant role in obesity.
Researchers participating in the Human Obesity Gene
Map project are in the early stages of determining which genes
contribute to obesity in people. Several alterations in normal
genes have been discovered in laboratory rodents and linked to
obesity in these animals. These genes include the ob or lep gene
and the Agouti gene. Researchers are working to find out if
these same genes contribute to obesity in humans.
Not all people who have obesity genes will be overweight.
Conversely, some people who are overweight will not have
these genes. This is because environmental factors also play
a major role in causing overweight and obesity.