Hey genius,
You can ONLY do an historical genetic tracing through the maternal genes (has something to do with RNA I believe). Remember that womens have only 1 Y chromosome, while men have 2. Maternal tracing allows you to back-track through that one 1 chromosome (which will also be in her mother and her grandmother and her great grandmother and so on and so on and....)
If you tried to do this through a paternal line, you could only trace back to the father (then you'd have to figure out which of the two grandfathers and then the potential 4 great grandfathers and then the potential 16 great-grandfathers and so on and so on and....)
Two tests, wise ass. I didn't know so I thought I'd ask.
Thanks for playing.
mtDNA Tests - 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, but it is hard to determine if this is a recent ancestor or one who lived hundreds of years ago. It is important to keep in mind with this test that a male's mtDNA comes only from his mother and is not passed on to his offspring.
Example: The DNA tests that identified the bodies of the Romanovs, the Russian imperial family, utilized mtDNA from a sample provided by Prince Philip, who shares the same maternal line from Queen Victoria.
Y Line Tests - More recently, the Y chromosome in the nuclear DNA is being used to establish family ties. The Y chromosomal DNA test (usually referred to as Y DNA or Y-Line DNA) is only available for males, since the Y chromosome is only passed down the male line from father to son. Tiny chemical markers on the Y chromosome create 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.