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.
Diseases Associated with Agent Orange. VA currently presumes that some diseases resulted from exposure to herbicides like Agent Orange. The Veterans Health Administration's Public Health website lists these diseases VA presumes are associated with exposure to Agent Orange or other herbicides during military service: