I figured they were bred like dogs, the Tamassrans know who often produces what for children and, breed them according to what the Antam needs. Just like I might breed dogs for intelligence, strength, temperament, size, good mothering instinct, boldness, color, etc... Then, being bred for a specific purpose, I would raise and train those dogs to that and not much else beyond the basics they needed to get along with other dogs and people. Same thing the Qunari do.
Of course some of them are short tempered, determined, foolishly brave jerks, they were bred to bee vicious guard dogs and, trained as such. Others were trained to win obedience trials, others for agility, etc... So yes, they would tend to be more one dimensional, single minded but that's good if everyone works together.
You have a dog that's a good mother, another a good hunter, another a good guard and fighter. put them together and, you have a pack that can take good care of itself. Alone none is very good at meeting all of it's needs but, together, they work great.