MDKO represents MOST DISTANT KNOWN ORIGIN

There are three types of genealogical DNA tests, autosomal (atDNA), mitochondrial DNA. A list of single nucleotide polymorphisms (SNPs) is returned.

A lab expert, DNA scientist, geneticist or molecular biologist, research student can conduct DNA test. In clinical lab this test is carried out to identify whether a pathogen is suspected in a patient sample. for example if a patient is suspected for HIV/AIDS, it can give positive result on DNA test, if the virus present in the blood.
DNA test is used for various other purpose, to find out the relationships, knowing any genetic defect of a baby, in forensics and so on.

Yes, get a court order for a DNA-test and he have to do it.