The Y-Chromosome. The y-chromosome is inherited more or less unchanged from father to son to grandson, indefinitely. Chromosomes contain the DNA that determines our inherited characteristics, and the y-chromosome is one of the 46-chromosomes in the nucleus of each of the cells of all human males. Most chromosomes, including the two x-chromosomes possessed by females, get recombined or shuffled each generation before being passed down to offspring. But the y-chromosome is unique in remaining more or less unchanged when passed from father to son. Thus while most chromosomes will contain a random mixture of genetic codes from one's grandparents and great-grandparents, a male's y-chromosome will be identical or nearly identical to that of his father, grandfather, great-grandfather and beyond for countless generations. Since surnames tend to be inherited in the same manner as y-chromosomes (from father to son or patrilineally), y-chromosome testing lends itself particularly well to surname studies.