Among ants, wasps and bees, any female larva may in principle become a queen, depending on the way in which it is fed (royal jelly, etc). It is usually assumed that all larvae have an equal chance of receiving this treatment. But I noticed this article in the UK Times this week, which suggests otherwise. In species of ant where queens mate with more than one male, the offspring of some males have a better chance than others of becoming queens. The preference has a genetic basis, but the detailed mechanism is unknown.
The original research, by Hughes and Boomsma, is in PNAS, but I have not been able to track it down.
Update from Razib: Hat-tip to a reader, Genetic royal cheats in leaf-cutting ant societies.