There is a condition called familial hypercholesterolemia. People who eat normal, balanced diets have LDLs levels in the 1000's (normal is less than 100). You can take a blood sample and watch the fat float to the top like cream in fresh milk.
They often die of cardiovascular disease when young. And it's just a genetic defect.
FH does not seem all that well understood. It runs in my spouse's family, multiple clinical/genetic diagnoses, but no history of cardiovascular disease. Doctors haven't been convinced whether intervening with statins is necessarily justified, especially in the face of any side effects.
My family on the other hand, generally normal bloodwork, normal BMI/fitness levels, and everyone dies of heart disease fairly young. At least it's one way to avoid cancer.
They often die of cardiovascular disease when young. And it's just a genetic defect.