Originally Answered: How far back can they trace your geneology on those sites?
A DNA test can show, approximately, your ancestors trail through the world since the evolution of your first ancestor, because you are female a test of your Mtdna will not show any paternal line at all, only your mother, her mother, your great grandmother etc., etc. You do not carry your father's Y-DNA and, either he, your brother, father's brother, or your father's father, or a male cousin on your father's side, would need to be tested to show your father's genetic origins.
Below is a reply I have given to a similar previous question, dna cannot tell you which country you originated in, only the probable area, or areas of the world your ancient ancestors passed through during their evolution.
Human cells contain 23 pairs of chromosomes: 22 pairs of autosomes, and one pair of sex chromosomes. Females carry a pair of X chromosomes that can swap, or recombine, similar regions of DNA during meiosis. However, males harbor one X chromosome and one Y chromosome, and significant recombination between these dissimilar sex chromosomes does not occur. Therefore, the non-recombining region of the Y chromosome (NRY) remains largely unchanged over many generations, directly passed from father to son, son to grandson, and so on, along with genetic variations in the NRY that may be present. Scientists can use genetic variations, such as single nucleotide polymorphisms (SNPs), on the Y chromosome as markers of human ancestry and migration.
It is very effective and the best companies will retest until they get a conclusive result.
If you have, say, just the first 12 markers tested($149 with FTDNA), that will give an indication of where you originated, the more markers you test on, the more information is gained ( for mtdna, your suggested geographic origin and your maternal deep ancestral ethnic origin, $129 with FTDNA) if you test on the maximumum of, say 67 markers ($349 with FTDNA), it is possible then to find a match to someone else carrying your own, or a different surname, and to prove a link where perhaps no "paper trail" exists. It can therefore pinpoint a place in which your ancestors probably lived in recent history but DNA does not, obviously,
have a surname attached to it, surnames have only been used for around 700 years and of course your DNA originated 10s of thousands of years ago. You can also have a SNP test which will help show the migratory pattern of your ancient ancestors, having said that, you can join a Surname project (e.g. with FTDNA) and receive discounted prices on your tests.
I recommend that you make yourself aware of the various tests available, and the costs with each testing company.
Plus, check out what is available to you after you have tested.
I used Family Tree DNA ,they were the first in the field (founded in 1999), have the largest data base, and do the testing for the National Geographic's Genome project, their "after sales" is excellent and I consider they are the best, but you have to make your own decision on that.
If you are female, you only carry your mother's Mtdna, and her mother's Mtdna, and her mother's Mtdna etc.,etc.,etc. and that will show only your mother's lineage (you will pass that Mtdna on to your daughters and sons, but your sons will not pass it on to their children). You do not inherit your father's Y-DNA.
If you are male, you inherit your father's Y-DNA, his father's Y-DNA, his father's Y-DNA, and so on back to your origin. You also inherit your mother's Mtdna, but you only pass your Y-DNA on to your sons.