After recently re-watching my favorite movies ever, the Back to the Future trilogy, I had some thoughts about Biff Tannen and his family knocking around in my head. I started writing out a Facebook post about it, and it turned into a treatise of sorts. This all happened extemporaneously, so some of this may not be perfectly accurate.
The following is way too many words about the Tannen Family Tree:
Let us consider the bully, Biff Tannen, from the Back to the Future franchise. It seems as though he had family members across the timestream, always there to be a foil for the McFly family. Each of the Tannen family members that we meet seem to be singularly egotistical and self-centered. But the existence of the family tree, and the fact that they have settled in Hill Valley for over a century suggests some interesting nuances to the Tannens. Note: This exploration does not include any content that may have been covered in the Back to the Future cartoon, video game, comics, or Universal Studios Ride, as these are of questionable authenticity at best.
Biff Tannen is a teenager in 1955. We know that he lived with his grandmother at that time, which suggests that his parents are either dead-beat or dead. The one interaction we see involving Biff's grandmother is when she gruffly yelled at him, asking where he was going on the morning of the Enchantment Under the Sea dance. Clearly Biff very likely picked up the gruff demeanor that is a hallmark of his family from his grandmother. Her attitude suggests that she barely tolerates him at best, and yet continues to provide him with a home while he works to complete high school.
Biff's grandmother is referred to as an 'old lady' in 1955, and she has a grandson who is approximately 18 years old. This suggests that she is significantly older than 40 or 50 years old, likely closer to 70. But even if we are generous and assume that she is 60 years old in 1955, that would mean that she was born in 1895. Ten years after the events of Back to the Future Part 3. Thus, it seems likely that she is either the daughter of (or married the son of) Buford "Mad Dog" Tannen.
The sheer fact that the Tannen name carried through from one generation down means that Mad Dog did not have a child through a one night stand with a tavern barmaid in the Hill Valley Saloon, but that the mother of his child knew him well enough to opt to take on his name and pass it down to their child. The same goes for Biff's grandmother and parents as well. With a family that is so very self-centered, it seems strange that they would produce stable family units.
This continues forwards to 2015, when Griff refers to Biff as 'gramps.' Clearly the family line continued in the same way - the family stayed together and continues to be antagonistic towards each other. What is surprising is that Biff was able to find someone to marry and pass on the family line. But we see that Biff had enough motivation and drive to opt not to drop out of high school and then go on to start his own business, which could be enough to attract a wife, likely someone with a similarly abrasive personality that could put up with him. Given that Biff is roughly George McFly's age and Griff is roughly Marty Jr's age, it stands to reason that Biff would have a child that is approximately Marty's age too. This character is conspicuously absent from the films, as Marty is the only McFly that does not have a Tannen as an arch-rival. Marty's rival is Douglas J. Needles. Perhaps Biff had a daughter, and she and Needles had a child out of wedlock before he went on to marry his wife Lauren and they had their two children together. Not having his father in the picture could explain why Griff is very familiar with his grandfather on the Tannen side, the same way Biff and his grandmother were close, yet at odds. Following this line of thought, the Tannens are once again the ones with the traditional family values, while Needles is the absentee father.
While the Tannens are unquestionably the villains of the Back to the Future franchise, for 6 generations the family has stayed together and passed on the family line in the same town in which they settled two centuries ago. When the history of Hill Valley is written, of course the McFlys will be noted as some of it's most famous residents, given a bestselling author and his Grammy-Award winning son, but the Tannen Family is just as much a part of the bedrock of the community. The adversarial nature of the Tannens brings the people of Hill Valley together like nothing else.
And when it comes to his family, a Tannen will never make like a tree and get outta here.