JACKSON, Mo. - Nathan Warmack wanted to honor his heritage by wearing a Scottish kilt to his high school dance. Then a principal told him to change into a pair of pants. What began with a few yards of tartan has sparked an international debate about freedom, symbols and cultural dress. More than 1,600 people have signed an Internet petition seeking an apology for the high school senior. Scots in the United States are assembling a traditional ensemble they hope the student will wear to the prom, and his family is trying to change the school's dress code policy. ''It's...