First of all, we must assume that the EBE’s technological development is at a level we can recognize. This does not mean that we are at a level where we could understand, or reverse engineer it, but at least we could distinguish it as technology of some kind. I would suppose that if the aliens were less than a thousand years ahead of us, we might be able to presume that they still worked with DNA, chromosomes, and gene therapy of some sort. Any more advanced, and all bets are off, and we don’t stand a chance of knowing anything about their science, or why they are here.
So, if we assume that these little guys are within our level of understanding, we already have a handy data set we can run. “Mitochondrial DNA (mtDNA) is contained in the cytoplasm of the cell, rather than the nucleus. This type of DNA is passed by a mother to both male and female offspring without any mixing, so your mtDNA is the same as your mother's mtDNA, which is the same as her mother's mtDNA. mtDNA changes very slowly so it cannot determine close relationships as well as it can determine general relatedness. If two people have an exact match in their mtDNA, then there is a very good chance they share a common maternal ancestor, this test along with the Y test which looks at tiny chemical markers on the Y chromosome that creates a distinctive pattern, known as a haplotype, that distinguishes one male lineage from another. Shared markers can indicate relatedness between two men, though not the exact degree of the relationship. Y chromosome testing is most often used by individuals with the same last name to learn if they share a common ancestor”. In the last ten years, these test have been voluntary taken by thousands of people who are attempting to study there family trees. If what Budd Hopkins and David Jacobs’. says about the extent of alien abduction is true, then we are bound to find a percentage of mtDNA test, and/or Y chromosome markers that are unusual, and point to non-distinctive patterns, and unknown relationships. Once again, this would work only if the aliens were not too far ahead of us, otherwise they would change human on a molecular level that we could not phantom. Just a thought.