ATLANTA - Martin Luther King Jr.'s youngest child lit a torch at her father's tomb last month to kick off a march advocating a ban on gay marriage, creating a strong image linking the slain civil rights icon to today's heated social debate. But just nine months earlier, King's widow defended the rights of gays and lesbians in a speech at a New Jersey college. King never publicly spoke on gay rights while leading the charge toward racial equality in the 1950s and '60s, but the clash over gay marriage has prompted people close to his legacy to...