What would cause fingernails to grown out bent? As if they are folding over sort of.?

Scroll down for pics: http://www.drstandley.com/naildisorders_鈥?/a>What would cause fingernails to grown out bent? As if they are folding over sort of.?
a genetic prob maybe but you prob smashed your finger at some point in your life and your 'scar' is that your fingernail grows in wrongWhat would cause fingernails to grown out bent? As if they are folding over sort of.?
Certain disorders of the nails but more commonly a long history of nail biting.
gravity, wear and tear.