Final answer:
Obesity caused by nature would be due to genetic factors. Genetic components that control appetite and metabolism play a significant role in the predisposition to obesity, displaying a notable pattern within families. Other biological aspects, such as certain diseases and medications, can also contribute to weight gain.
Step-by-step explanation:
Obesity caused by nature would be primarily attributed to genetic factors. While lifestyle and environmental conditions do play a significant role in the onset of obesity, the question specifically mentions 'caused by nature', which directs us towards the biological underpinnings of obesity. In particular, various genetic components that influence appetite, metabolism, and body's energy storage mechanisms are known to predispose individuals to obesity when they have access to an abundance of food energy. Studies indicate that when both parents are obese, the likelihood of their children also being obese can be as high as 80 percent, which underscores the genetic influence on this condition.
Moreover, certain diseases and medications can also contribute to weight gain. Diseases like hypothyroidism or Cushing's disease can affect metabolism, and medications including some antidepressants and steroids can increase the risk of obesity. However, it's important to note that the incidence of obesity purely from genetic or medical causes is less common compared to the cases involving a combination of genetic, lifestyle, and environmental factors.