Kerr was born in Beirut, Lebanon to Malcolm H. Kerr, an American academic who specialized in the Middle East, and his wife, Ann (Zwicker). He has three siblings. His grandfather, Stanley Kerr, volunteered with the Near East Relief after the Armenian genocide and rescued women and orphans in Aleppo and Marash before eventually settling in Beirut. Kerr spent much of his childhood in Lebanon and other Middle Eastern countries. While in Beirut in the summer of 1983, he met a number of US Marines who were later killed in the Beirut barracks bombings. Kerr attended Cairo American College in Egypt, the American Community School in Beirut, Lebanon, and Palisades High School (now Palisades Charter High School) in Los Angeles, graduating in 1983.