Is it possible for an underweight person to have high cholesterol?

Cholesterol : Yes. Of course. Cholesterol problems come from genetics and have very little to do with life style.

Uncommon but possibl: High cholesterol has two major sources: diet and heredity. If you 'picked the wrong parents' you can do everything right and still have high cholesterol. Diet still plays a role. High cholesterol can also be cuased by kidney or thyroid diseases, which can be present in thin people.