Typically when I tame a new combat pet I check to see what family it falls under. What the differences are between these pet families remains a mystery at this point in beta, but as I gain more information I'll update this posting because it has my curiosity peaked. I have a few ideas though, I think there may be a correlation between pet families and the type of attack or damage it does. For instance, The skill Destruction reads: % boosted pet damage for x seconds after critical blow done with Tear, Fang, or Strike. So perhaps Tear, Fang or Strike has a part to play. Another idea is that the food your pet will eat is tied into the pet families. Perhaps there are pet stats that we cant check yet such as speed, armour, etc.. that are affected by what family the pet falls under. So far here are the Pet Families that I have found:
-Wolf
-Scorpid
-Spider
-Crocolisk
-Raptor
-Heyena
-Cat
-Arachne
-Canine
-Crocodile
-Scorpion
-Wolf
-Scorpid
-Spider
-Crocolisk
-Raptor
-Heyena
-Cat
-Arachne
-Canine
-Crocodile
-Scorpion