I agree with Medusa, they are hereditary in some cases, sometimes it is allergys, sometimes something else,but mostly hereditary, my husband has them really bad, looks like someone punched him in both eyes, but as he wears glasses that hides them, my daughter has them a little too, but not too badly, but they show up when she is tired or sick mostly,and most of my husbands family have them, also my son's girlfriend has them and hates them, i am sorry i do not know of any product that really works, but concealer is the way to go, i use one from avon, and it works well, although i don't have the dark circles, it is good for all sorts of other things you wish to hide, good luck with your search.