. . "Thus, the State???s quarrel cannot be that age is a personal characteristic, without more.9 The State further argues that age is irrelevant to the custody analysis because it ???go[es] to how a suspect may internalize and perceive the circumstances of an interrogation.??? Brief for Respondent 12; see also Brief for United States as Amicus Curiae 21 (hereinafter U. S. Brief) (arguing that a child??" . .