The research analysed the mitochondrial DNA (mtDNA), that is present in all human beings and passed down with only minor mutations through the maternal line. The other is the Y chromosome, that is present only in males and passed down with only minor mutations through the paternal line. Both can show from what part of the world a matrilineal or patrilineal ancestor of a person came from, but one can have in mind that they are only a fraction of the human genome, and reading ancestry from Y chromosome and mtDNA only tells 1/23rd the story, since humans have 23 chromosome pairs in the cellular DNA.