well, yes, droopy eyelids can be hereditary. And there are some causes which can lead to droopy eyelids. For example, weak levator muscle, paralysis of some nerves, even Injuries such as fracture of the skull bone between eye socket and nose can cause droopy eyelids. If your situation is hereditary, you may need to have some surgeries to cure it. And for the normal one, you can try some ways to treat it. For example, you can just put the cool teabags on your eyes. And repeat this for a few days. It can relieve the situation. By the way, stop rubbing your eyes, for that will lead to droopy eyelids. So just pay more attention to it.