In December, Danielle and Alexander Meitiv had let their 10-year-old son Rafi and his 6-year-old sister Dvorah walk one mile home through Silver Spring alone. The kids got picked up by the police, who then turned the case over to child protective services. The Meitivs, as it happens, are “free-range parents” who have a very coherent philosophy about giving children more independence. They had let their children walk home alone that day only after practicing, and felt the kids were ready.