What causes a person's fingernails to grow out flat or curled?

Question

I have two nails that do this. One that flattens out and goes downward, the other tries to go flat and on one edge it starts to curl.

Answer 1

I HAVE A BOOK ON THAT . SOME OF IT COULD ME YOUR LUNGS>>

Answer 2

If you File Your Finger nails, Where It doesnt Grow Sharp/ Curled/ It would Make a Diffrence, also, you might want to Trim your Nails to, Or perhaps Visit a Beauty Salon, Who does Nails, I heard Eating Jello Helps Nails To, Good Luck.