Earlier investigations have determined that 53 per cent of MS risk is strongly attributable to external factors in the environment, and that as much as 20% of MS cases could be linked to smoking. Cigarette use and high body mass index (BMI) are leading global drivers of many non-infectious diseases. https://neurodaily.net/2020/12/26/childhood-obesity-could-increase-the-risk-of-multiple-sclerosis/