It is not entirely impossible to trace family records IF the family had records or there was a means at the time and their survived. To date we have traced all of the branches of my family to before they came to the New World, the oldest confrmed was a tax collector in Paris in the 15th Century and one of his younger sons was the first to come to the New World where he worked with or for some Jesuits. From there it was easy since the family didn't leave the area they settled in for several hundred years.
Oh yeah, if your family is lazy and doesn't move for several generations then it is pretty easy to trace them as well
