Having a graduate school education, plus an MD gives me a good insight to this. Cholesterol makes up part of the cell membrane. It is also the precursor for steroid hormones. It makes them all! including cortisone, male and female sex hormones and aldosterone, a steroid that helps control sodium levels and blood pressure. Your liver is the primary producer of cholesterol. That is why genetics seem to make a difference. Maybe we should be looking for an, natural, antibiotic in those of us that don't smoke!