Final answer:
The increase in obesity rates despite stable human genetics over the past century points to a dominant role for environmental factors in obesity, although genetic predisposition plays a role as well. Factors like diet, physical activity, and socioeconomic conditions heavily influence the development of obesity.
Step-by-step explanation:
Considering that the human genome has not changed markedly in the last century while obesity rates have increased, it suggests that environmental factors play a significant role in the occurrence of obesity. However, it should be noted that genetics also play a critical role. Various genes control appetite and metabolism, predisposing individuals to obesity when ample food energy is available. The likelihood of a child being obese is greatly increased if both parents are obese, indicating a strong genetic link.
Environmental factors such as socioeconomic status, availability of healthy foods, physical activity opportunities, and modern lifestyle changes contribute to the energy imbalance that leads to obesity. Increased calorie intake, especially from high-fat and high-calorie fast foods, combined with decreased physical activity, are central environmental influences. Therefore, while genetics provide the susceptibility, it is the environment that often determines the expression of obesity.
In conclusion, both genetic and environmental factors contribute to obesity, with environmental factors playing a more prominent role given the rapid changes in obesity rates despite relatively stable genetic makeup. Hence, the statement that 'Environmental factors play a significant role in obesity' is the most accurate amongst the given options.