When I was a kid I used to eat dirt and sand. I craved it why?!

only if she suffers from some form of malnutrition. my wife used to eat dirt as a kid. she also ate dandelions and some weeds. i think she lacked something significant in her diet. our son never ate dirt.

I think alllll kids eat dirt and sand at some point. I remember once I shoved a couple of handfuls of sandbox sand into my mouth to eat too. It's partly a learning experience a result of curiousity. Babies especially use their mouths to explore things. It's a sensitive part of the body and one of the main things we control and actively use, like our hands.
As for it being genetic... I've never personally heard of such a thing but it could be! That's an interesting thought. But like I said, I think all children eat dirt and sand at some point in their lives, even if just once, even if just an impulse. What could be genetic is your taste buds and a craving for it, though. :)

General knowledge I learned in school

There's a condition where you feel the need to eat dirt can't remember it though, it's something like terraphage though. Also you could be lacking in some sort of vitamins or minerals found in dirt. The chances of your daughter having the problem too is probably slim. Also little kids tend to experiment with things such as eating dirt, bugs, and/or plants.