Some of the lines are very difficult to trace. The many marriages, mistresses and illegitimate children of some of the historial figures make the job tough. Some sources only recognize legimate heirs. If you can trace your family history back to 1500 or so you have done a great job.

Prior to 1500 some families did not have surnames, in others the surnames and spellings change from generation to generation. In some famous cases families (Stewart) have chosen to carry the mother's surname.