Someone on another post asked what causes atherosclerosis, so here is the official NHS line.
Exactly how arteries become clogged is still unclear, although the following things increase your risk of atherosclerosis:
smoking
a high-fat diet
lack of exercise
being overweight or obese
having either type 1 or type 2 diabetes
having high blood pressure (hypertension)
having high cholesterol
nhs.uk/conditions/atheroscl...
Most research that is done on heart disease has agreed that these are risk factors, but they all act together. So your total risk will be calculated using a Framingham risk score or Qrisk.
The interesting this is that despite my supposedly high cholesterol I score 3% on a Framingham risk score and 6% on a Q risk calcuation - not high enough to merit being prescribed a statin.
However if you have FH, or possible FH, official NICE guidance is that these risk calculators should not be used and you should be prescribed a statin - in fact you probably need to be prescribed a high strenth statin. Because you are automatically at high risk.