The 18+ rule was to keep the Reddit Hamdmins at bay. Since we're not on Reddit anymore, FPH is open to anyone. The rule about not posting pics or stories of children under 18 is gone too, so saying anything in defense of a fat child, no matter how young, is considered fat sympathy and can get you banned. AFAIK the mods won't verify anyone under 18, though, just to avoid any concerns about the potential of inappropriate photos of underaged persons.