Hi there,
I know little about genetics, but nothing about toe nails
So far, there's no gene identified that would be responsible for the shape of toe nails and registers you're writing about are just kind of forming. Researchers have been collecting data on specific diseases and it's only a couple of years they've started to collect all sorts of data (like for example the shape of the toe nail).
Anyway, once such data is collected there's a good chance that gene you're curious about can be identified.
