That's a tough call. On one hand, its bad human behavior to let your child(unattended) hug a dog they aren't familiar with but also it's bad dog behavior to bite a human under any circumstance and unusual to bite without growling first. Most dogs don't appreciate being hugged by people they don't know very well, so kind of a natural response on the part of the dog. I would put blame more on parents for leaving child with a dog they weren't accustom to or the pet store for not better screening their dogs for behavior issues. That dog should of never been given the opportunity to bite...