Natalie Raanan will be 18 years old next week. But what should be a time of celebration and planning for her future has turned into a time of desperation and sadness, said her brother, Ben Raanan of Denver, as Natalie and her mother, Judith Raanan, are believed to be hostages of Hamas in Gaza. Just 13 days ago, Natalie and Judith Raanan, who live in a suburb outside Chicago, were visiting Judith’s mother in Nahal Oz, a kibbutz about a mile from Gaza in southern Israel.