Half siblings definitely looks like a good possibility--the cousins look like cousins, the aunt looks like an aunt, and the suspected half sibling looks like a half sibling--all of those people came up in the range you'd expect to see.
Network President Jenny LeFevre, Agent Orange Victims and Widows Support Network, attributes more than 250,000 deaths to Agent Orange, a toxic herbicide the U.S. military sprayed over Vietnam from 1962 to 1971.
Agent Orange was a powerful mixture of chemical defoliants used by U.S. military forces during the Vietnam War to eliminate forest cover for North Vietnamese and Viet Cong troops, as well as crops that might be used to feed them.