I know nothing

Ok, I know nothing about genetics! Me my Dad and my daughter have an identically shaped toe nail which is obviously inherited, i.e. same shape same toe. By looking at out genes is it possible to figure out which gene causes this? Is this of value? if there was a register of such things surely it would enable researchers to figure out which genes did what and therefore highlight which ones were more important for medical research! Does a register exist? As I said "I know nothing!!!!"