I just learned i have hi cholesterol like both parents, aunts, sister. doc said it might be due to stopping estrogen. is that the cause or is genetics?

Many causes : Cholesterol is a vital and misunderstood component in our bodies. Cholesterol protects cell membranes from oxidative stress, is used to make sex hormones, vitamin d and bile salts. Some people are genetically predisposed to various metabolic problems which requires higher levels of cholesterol to maintain normal function. Hypothyroidism will raise your cholesterol. Stopping estrogen? Possibly.

FH: How high are your and your family members' cholesterol levels? Familial hypercholesterolemia (FH) might be present and would need to be treated aggressively to avoid serious complications. Speak with your doctor and see the link for more info: https://thefhfoundation.org/