TUBA CITY, Ariz. - Hataałii Tiisyatonii "HT" Begay, a Native American boy who is Diné, or Navajo, rolls toy trucks around in the dirt. He chases chickens into their coop. He pauses to watch his dad deftly gut a sheep for a ceremonial feast. Then he climbs onto a picnic table with his brother and cousins, chanting "Lava!" while pretending the ground has turned into molten rock. To his family, HT is a typical 5-year-old - a smiling, curious, busy blur who roams across his family's ranch, where the