What are the causes of high cholesterol?

Lots of reasons: Genetics, a diet high in calories/fat, sedentary lifestyle, underactive thyroid, and diabetes are some.

Thyroid + gall bladd: Healthy gallbladder and liver uses cholesterol to make bile so normalizing them will normalize cholesterol. Cholesterol is formed in liver under influence of thyroid. Cholesterol is needed to make hormones in body if hormones are unbalanced (high estrogen states) stresses thyroid which slows down, increasing cholesterol and if gallbladder does not work and thin bile liver backs up cholesterol.

Diet & liver metab: The two sources of cholesterol are dietary (you eat it) or your liver produces it. Statins are medications to reduce liver production.

Genetics & Lifestyle: These are the two main causes of high cholesterol. For the average individual only about 10 to 20% of your circulating cholesterol is from dietary sources, the remainder is manufactured by the liver according to your genetic "set point." foutunately the are a number of options available to control both sources of cholesterol in the body.

Poor diet, obesity: & genetics & smoking.