I think lots of factors are involved, including hormones. I don't know if there's much evidence for lowering cholesterol overall but oestrogen helps with lowering bad cholesterol and boosting HDL, the good stuff. It also relaxes blood vessel walls and reduces inflammation in the body, which is a big part of heart disease. Heart attacks and heart disease levels shoot up in women after menopause, as oestrogen really does protect us. Whether or not HRT helps in this respect is not clear yet, as most of the data relates to the old forms of HRT. Not enough studies have been done yet looking at the effects of body-identical/transdermal HRT but certainly synthetic progestogens are a problem.
Triglyceride levels are thought to be as important as cholesterol as a risk factor, so any cholesterol test needs to have the full breakdown of the different types to be meaningful.
For people interested in looking at alternatives to statins, I can recommend A Statin Free Life by Dr Aseem Malhotra, a cardiologist and statin sceptic, who examines the evidence and gives advice on diet, exercise, stress management etc. Worth trying your local library - mine has it, although I did buy my own copy in the end.
