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.
Use of Agent Orange. During the Vietnam War, the United States sprayed approximately 20 million gallons of plant-killing chemicals known as herbicides in Vietnam to expose enemy hiding places, destroy crops, and clear areas around U.S. military bases.