We know that there are ten times as many Sranc roaming the Ancient North today as there were during the First Apocalypse. Yet Sranc are always depicted as male, so would appear to be incapable of mating with one-another.
There is also a Sranc who says, in reference to the Old Fathers: "Father… father! We have no fathers save the earth!", which suggests the Sranc somehow gestate within the earth (like Orks!), but I seem to remember somebody mentioning a reference to female Sranc, so perhaps that is wrong.
It is possible that all Sranc spill out from Golgotterath, but if that is the case how are there wild Sranc clans who don't even know who the Inchoroi are?