You know....all the time I hear "it's all in how you raise them." Well, it's not. As a foster mom, I've raised puppies from seven days and up. With a couple of them, I could tell from the time they were very very young that they were going to be unsuitable for families with young children. They were hand shy at a very young age, not interested in people from a very young age, accepting of but not solicitive of praise and affection, attached to a single family member (or particular family members), not accepting of visitors or unsolicited affection from anyone other than a single or particular family members. All red flags that were present or developing from birth, and undeterred, despite lots of behavorial intervention from an experienced owner at a very early age. But that kind of insight comes from A LOT of experience with A LOT of different puppies (of varying breeds and temperaments). Dogs, like children, are born with a personality, and early intervention and training can mitigate the negative characteristics and encourage the positive ones, but no amount of training or intervention will change a dog's inherent temperament.
I have one dog that I've raised from infancy. He was heavily socialized as a puppy both with other dogs and with people. He is fine at the dog park with other dogs. He is loving and sweet around all of our immediate family members, and tolerant of a few frequent visitors. But he will never be safe around children or strangers. He must be put away when unfamiliar visitors visit. Even with us, we must be careful with him if he's in high alert mode -- I would never grab his collar or try to mandhandle him if he was scared/barking/anxious/predatory. I get his leash and leash him up, calm him and move him to his kennel. All of that "Be Alpha! Show him who's Boss!" viewpoint would result in a bite to the face. We calmly mangage his behavior; we do not control who he IS.
While there are techniques you can use to manage a dog with issues (as we do), NONE of that really matters when you're dealing with a dog/child situation. I'm pretty harsh when it come to rehoming, but when a family is put into a situation where the dog might bite a child (and thereby earn a quick trip to the needle) then the dog must be rehomed for it's own safety and for the safety of a child (who is incapable of either protecting himself or participating in any preventative training).