From that article:
"Dr. Weinstock goes even further. “Children should be allowed to go barefoot in the dirt, play in the dirt, and not have to wash their hands when they come in to eat,” he said. He and Dr. Elliott pointed out that children who grow up on farms and are frequently exposed to worms and other organisms from farm animals are much less likely to develop allergies and autoimmune diseases.
Also helpful, he said, is to “let kids have two dogs and a cat,” which will expose them to intestinal worms that can promote a healthy immune system."
Our mum would say we are expected to consume a bushel basket of dirt in our lifetime. She gave us a head start: "Go play in the dirt!"