I think it really all depends on the dog. Very tiny yorkies probably shouldn't be around kids for the risk of them getting hurt. My yorkie had never been around small kids until she was over a year old. My little cousin saw her for the first time and she ran to him with her tail wagging. He ran to her with his hand going up and down in a patting motion. When they met in the middle she immediatly fell to the floor, rolled on her back, and let him pat at her tummy while she wagged her tail and tried giving him kisses
But Layla is a very gentle dog, she has never snapped at anyone