common brown snakes give live birth so why not Au'Ra? but they definitely come off as more mammalian than reptile... as for the lack of children NPCs in ARR i think you could attribute it partly to the fact that its post calamity and having children NPCs being front and center in the wake of such a disaster would be a tad depressing at the very start of a game like this... tho there are children when you learn the harvest dance in Gridania which i suppose was to give a bit more realistic depth... and lets be honest as an adventurer wandering the land most of your dealing would be with adults... and a random strange adult walking up and talking to children everywhere would be a bit creepy to the locals... good luck getting help when people think you might be some pedophile.