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.
Operation Ranch Hand and Agent Orange. From 1961 to 1972, the U.S. military conducted a large-scale defoliation program aimed at destroying the forest and jungle cover used by enemy North Vietnamese and Viet Cong troops fighting against U.S. and South Vietnamese forces in the Vietnam War.