My burning question about tracing my ancestry is this: without a firm sample directly from the ancestor's family, how do you really know? Let's say we take the samples of my aunt and other elderly members of our family and we are able to prove linkage to them. Now what? Does that prove a link to the folks who settled America in the 1700's? It does not, does it????
In genetic genealogy we have two avenues of comparing results for the male Y-Lineage: STR and SNP. Short Tandem Repeats are designated by DYS markers. These are the 12, 25, 37, or 67 marker results each individual gets when they test. The genetic genealogist can compare these DYS markers with other tested individuals within that Surname and without. Related individuals within a Surname can often be spotted via this method.
SNP stands for Single Nucleotide Polymorphism or "Snip". Snips are used to categorize groups of related people with various diferent surnames into larger related groups. From these two methods the genetic genealogist can often trace ancestry.
Your aunt has mtDNA. Females have mtDNA. Males have Y-DNA and mtDNA. If your aunt and your mother have the same mother (your maternal grandmother) then your mtDNA will match them. That mtDNA result can be placed into a database and matched with other tested results. Through these comparisons genetic genealogists can and do make links to other family members and larger groups of related individuals.