The journal "Nature" has published a report by a genealogical research team delving into the mysteries of human ancestry. Their findings state that everybody alive today - no matter where in the world - shares a common ancestor who lived 2-3,000 years ago.
Considering how much she got around, that ancestor's name is probably "Xena".
Team member Steve Olson said, "People are much more closely related to each other biologically than we've suspected in the past."
Another member of the team, Yale mathematician Joseph Chang, claimed that because a person's genes are diluted by half every generation, it's unlikely you share any of the same genes with a forebear who lived even tens of generations ago, Chang explained. But that person is still your genealogical ancestor, even if you are not genetically related.
Of course the scientific laws of the real world don't apply to Toobworld, and vice versa. Otherwise, there would be no secret bases on the moon and time travel in the TV Universe. And we would have manimals and automen roaming about in our midst, saying "Can you hear me now? Good."
In the TV Universe, characters not only share genetic material with ancestors tens of generations back, they can look exactly alike as well. We are used to seeing a character's parent and sometimes even grandparent looking like them, but this seeing double can go back even farther on the family tree. AJ and Rick Simon had carbon copies forebears dating back to the American Revolution.
('Simon and Simon')
And Samantha and Darrin Stephens are both genetic echoes of prehistoric ancestors who also shared the same names. And as if by kismet, these primeval twins also fell in love and married. Samantha's ancestor was even able to practice witchcraft.
[We know it couldn't be the modern-day Sam and Darrin on a magical pre-history tour of Bedrock. It has been stated with certainty that witches can't go beyond that point in time when they were born, or else they risk losing their powers. And the proto-Samantha had full use of her Neanderthal nose-twitch.]
('Bewitched' & 'The Flintstones')
"We make mistakes. Genetic manipulation or not, nobody's perfect."
Captain Jean-Luc Picard
'Star Trek: The Next Generation'
[This was based on an article by Paul H.B. Shin, which was originally published in the New York Daily News on October 3, 2004.]