Thin toenails that don't grow?

Why won't my toenails grow.They are very thin I mean you can literally ripped them off with just a simple touch.They have vertical and horizontal lines going every where.They take forever to grow and when they do,before you know, it rips of even by my beddings.I don't know what do any more.I never show my toes because they are hideous with no nails.I thought maybe if i show them more the sunlight light might make them stronger.My toes have never seen the light of day ever since I can remember I never showed my toes.Not even in elementary school around my friends I was too insecure about them then too.My dad has similar toes but the thing is I don't know if his toenails grow because he rips his nails off just for fun before they get a chance to.(EWWW)My mom has very hard toenails and she is always clipping them.What should I do?Yes I drink tons of milk with a healthy diet and take vitamins daily.