As Thanksgiving approaches, families around the US are gathering to give thanks, eat food, and annoy the hell out of one another. When your family starts arguing about your uncle's drinking, your sister's convict boyfriend, or your cousin's decision to drop out of college, be glad that you don't have to contend with killer robots, mad scientist parents, or sibling rivalry turned homicidal. We list science fiction families that will have you giving thanks for the mundane problems of your own dysfunctional clan.
The Skywalkers (Star Wars): The Skywalkers are more or less the gold standard for family dysfunction. Putting aside that twins Luke and Leia have the hots for one another, Papa Vader chopped off Luke's hand, nearly killed him, and annihilated Leia's entire home planet. Makes those family dinners pretty awkward.

Adding Han Solo's DNA to the family tree doesn't improve matters, as his Force-sensitive offspring Jaina and Jacen just end up battling to the death.

The Connors (Terminator): If it weren't for all the time-traveling killer robots and the apocalyptic future, Sarah Connor's treatment of her son John would be considered abuse. She intensely isolates the future leader of humanity's Resistance against the machines, and encourages in him a level of paranoia, violence, and general criminal behavior that most parents would tend to avoid. And the future John will befriend Kyle and Derek Reese, never revealing to them that they are his father and uncle respectively. And, given that John and Sarah spend so much of their lives running from Terminators, they develop warm fuzzy feelings for a couple of them. A reprogrammed T-800 serves as John's first father figure and Cameron proves a vital (and confusingly sexy) addition to the Connor clan.

The Ventures (The Venture Bros): Rusty Venture is a walking dysfunction all on his lonesome. Unable to live up to his father's impossible example, Rusty turned into a pill-popping, underachieving neurotic with a shaky moral center. And it doesn't help that his brother JJ (who played Abel to Rusty's Cain in the womb) is successful in the very areas where Rusty fails. Conversely, Rusty treats his own children with less than benign neglect, cloning replacements whenever they are killed (which is often) and leaving their emotional care to the ultra-violent, highly promiscuous spy Brock Samson.
The Cylons (Battlestar Galactica): The Significant Seven models of Cylon are a big, dysfunctional family in their own right, albeit one that pulls out the heavy artillery when a disagreement over the family pets goes to far. But it's within the individual model lines that the dynamics get particularly screwy. When everyone shares the same face and the same programming, personal identities and relationships tend to get blurred. At least one of the Sharons wants to be Sharon Agathon so badly that she sampled her fellow Eight's memories and put the moves on her husband. And then there's this scene:

The Mulder/Spender Families (The X-Files): It's little surprise that Fox Mulder developed an interest in conspiracies given how much of his upbringing was based on lies. Bill Mulder, the man Mulder believed to be his father, traded Mulder's sister Samantha for an alliance with a group of alien colonists. As result, Samantha is repeatedly cloned and Mulder develops an obsession with aliens and conspiracies. And no one told Mulder that his biological father is, in fact, the Cigarette Smoking Man, the ruthless conspiracy agent who has antagonized Mulder throughout his FBI career. The CSM has Mulder's partner Dana Scully abducted, tries to ruin his career, lies to him about his sister's fate, and generally torments him. Still, that's nothing compared with the CSM's treatment of his other son, Mulder's half brother Jeffrey Spender. The CSM berates Spender for being inferior to Mulder, shoots him, and authorizes his agents to perform horrific and disfiguring experiments on him. It's all enough to make Mulder's emotionally distant relationship with Scully, the mother of his own child, seem downright warm and fuzzy. Mama Ripley and the Alien Hybrids (Alien Resurrection): Ellen Ripley spends three movies ensuring the destruction of as many Alien xenomorphs as she could take a flamethrower to. Then, in the fourth film, her clone gestates and "births" an Alien queen. Tainted by Ripley's human DNA, the queen develops a womb, letting her give birth to an Alien daughter of her own. Like so many children, the newborn Alien digs grandma a whole lot more than mom, and matricide ensues. Ripley repays her grandchild by getting it sucked out into space, but not before they share a vaguely erotic moment:

The Petrellis (Heroes): The Petrellis are generally marked by three characteristics: they all have superpowers; they all have secret parents, siblings, or offspring; and they are constantly trying to kill one another. Claire shoots her uncle Peter. Peter shoots his brother Nathan. Patriarch Arthur plans to murder his son Nathan. And brothers Peter and Sylar are constantly trying to kill each other. Only matriarch Angela Petrelli (wife of Arthur and apparent mother of Nathan, Peter, and Sylar) stays out of the attempted murder racket, though she's pulling most of the other family members' strings.

Just about everybody in Dune: The noble houses of Dune are dysfunctional precisely because they resemble so many of history's noble families: propagated through inbreeding, filled with members of uncertain parentage, and driven by political marriages so that you can't help but go to war with your cousin. That many of the series' characters were conceived as part of the Bene Gesserit's breeding program helps to further entangle the families. And the spice agony, which causes a person to take on the memories (and sometimes personalities) of all their ancestors, allows a person experience the full spectrum of familial dysfunction without ever leaving their own head.

The Endless (Sandman): Sibling rivalry is bad enough without having siblings who are the immortal embodiments of the world's greatest forces. Dream gets along fine with his sister Death, but their sibling Desire, in concert with its twin Despair, interferes constantly in his affairs, and takes great pleasure in trying to bring the wrath of the Furies down on Dream's head. Although generally fond of youngest sister Delirium, the Endless tend to ignore her incoherent babbling until it is far too late. And Destiny quietly watches on, acting only when his great book tells him he will do so. The only sensible one seems to be Destruction, who retired from his position and stays out of family matters.