On Movies: Boy uninterrupted: The life of actor Ellar Coltrane, from age 7 to 19, is the blueprint of "Boyhood"

It's a muggy Monday in July and the Boyhood family has assembled one more time at a SoHo hotel: writer and director Richard Linklater, actors Ethan Hawke and Patricia Arquette, and Ellar Coltrane, a gangly soon-to-be-20-year-old with pierced ears and a nose ring.