Researchers can build mathematical equations (sometimes referred to as structural equations) that predict health outcomes based on health factors. Those mathematical equations can then be used in online calculators.
This link takes you to a government-sponsored calculator based on the Framingham Heart Study. It estimates 10-year risk for “hard” coronary heart disease outcomes (myocardial infarction and coronary death).
As you will notice, the link above does not take family history of disease into consideration. A different risk calculator, linked here, estimates a risk score called the Reynold Risk Score. It takes hsCRP (high sensitivity C-reactive protein, an inflammation marker) and family history in addition to the Framingham parameters in its risk score calculation.
Neither calculator asks for LDL cholesterol levels. I wonder why.