While a surname itself may give us incomplete or misleading or, at best, only general information about the origin of a family, DNA-testing can give us concrete evidence for identifying and separating family lines. Y-chromosome DNA testing is especially helpful because the male Y-chromosome is handed down, father to son, unchanged through the generations, except for rare mutations which, in themselves, can be helpful indicators of branching.

To say we get half of our DNA from our Father and half from our Mother is not quite true.  One tiny piece of our DNA is inherited only down the female line. It is called Mitochondrial DNA because it is held as a unique circular strand in small tubular packets known as mitochondria that function rather like batteries within the cell cytoplasm. The overwhelming majority of a human's DNA is contained in the chromosomes in the nucleus of the cell, but mtDNA is an exception. Individuals inherit their cytoplasm and the organelles it contains exclusively from their mothers, as these are derived from the ovum (egg cell) only, not from the sperm. Mitochodrial DNA testing will give females and males their direct female lineage, which is mother to mother to mother and on (for males this is only your mother's mother and her mother and on.)

The accessibility and affordability of family DNA testing is doubtless the greatest technical advance in the history of genealogical research because -- at long, long last -- we have a tool to break down those brick walls!