Your Guide to DNA and Genealogy
DNA is not just for scientists any more! Genealogists are using DNA as evidence to establish the probablity of -- or disprove -- a lineage.
Y Chromosome DNA is passed father to son; you must have a straight male line for this test. Female descendants can make use of this only by asking a brother, cousin, father or some other established male relative tested. Surname studies are built on Y chromosome DNA.
Mitochondrial DNA is passed mother to child... male or female... so can be useful to determine if a female ancestor is the same for any two people, but because women change surname on marrriage, can't be used for surname studies. Because mitochondrial DNA is more stable, it can be use to determine ethnic place of origin of the maternal line.