I suppose as far as there are records, or an oral history like the one Alex Haley's family passed down as described in "Roots".

Personally, I can trace back to my maternal grandmother's great-grandfather.

I went all the way back to the bible , but that was because I have a long line of kings in that line and they kept really good records.

It is now 26 years since I began tracing my own family tree and the earliest ancestor I have traced myself was in 1653 in Yorkshire, England. This was mainly due the fact that the family remained within a ten mile radius for 400 years making it far simpler.

From my own genealogy experience I would say that tracing a family back to the early 19th century can be fairly simple if you have access to the census returns. This is depending of course on the uniqueness of the surname, the amount of travelling your family did and their financial/social status. By this I mean that there is more documentary evidence on the rich, the poor or the criminal ancestors!

Prior to the 19th century it is far more difficult to be postive that you are indeed tracing the same family especially if they have a common name such as Smith or Brown. In small villages it is easier to establish how each person in related but in towns and cities there can be several unrelated familes with the same surname making it very difficult to figure out.

Church records first began in England in the 16th century and a lot of these survived so it is quite possible to get back that far depending on the individual family but prior to the 16th century you have to rely of manorial records which are to be honest few and far between and will usually only mention the upper classes.

So to sum up your question "How far can a family Genealogy go?". It is possible but rare to go back earlier than the 16th century but most family histories become more difficult to trace prior to the 19th century.

I'm adopted, so I consider myself the root of my family tree. I guess I had the option to trace my adoptive family line or try to sort out the biological nightmare that was my real family, but I opted for the fresh start approach.

It works for me.

I can trace my ancestry all the way back to Charlemagne.

My grandmother is descended from all the kings and queens of England and because they were such good record keepers it's easy for me to trace this one line of ancestry back to Charlemagne.

The reality of ancestry though is that we have many, many threads of ancestors and that we are all related.

If you use a DNA tracking service, you may find your ancestral path to go back many thousands of years, tracking your genetic migration, pointing out relationships to peoples all over the planet, and actually identifying individuals all over the world you may be related to.
Ancestry.com can provide you with the needed tools