This video shows that being overweight can be due to genes. For some people, being overweight is not because they lack of willpower, but lack of hormones, such as leptin, that signal brains to stop eating. However, lack of leptin is not the only factor that cause obesity. Teresa Godfrey, the obesity patient in this video, has a mutated and non-functional MC4 receptor. This null mutation causes her to eat 2 to 3 times more than normal people Biotechnology such as cell tissue culturing is shown in this video.