The Freudian Excuse has been used by defendants in real-life court cases, although nowhere near as often (or as successfully) as fiction make it out to be. This is mainly used in penalty phase of capital murder trials, and even then, this is only used to avoid a death sentence. It's not really a legal defense, except as a set-up for some form of insanity plea. No matter how much you explain your actions ("I'm only a murderer because daddy beat me" as analogue to "I'm only a thief because I have no money"), explanations don't form a legal excuse.
Unfortunately in real life, while it is not always true, people are actually more likely to do bad things if their parents did them. For example, if someone was abused by their parents, they will be more likely to abuse their own children. This is most often not due to the person being evil, but because the person in question knows no other way.
While it's certainly no excuse for his actions, Adolf Hitler had an abusive father note Whom he believed had Jewish heritage, although it's ambiguous whether he actually did. and wasn't let into an art school.
While trying to get in art school in Vienna, where anti-semitism was all the rage, he run into non-assimilated orthodox Jews for the first time. In Mein Kampf, Hitler even confesses that up to that point he had considered Judaism nothing but a religion and believed that someone could perfectly be Jewish and German.
Hitler also grew up at a time when nationalism and nation states was all the rage - but in Austria-Hungary, a multiethnic semi-absolute monarchy relic from the century before, poorly run and awfully decadent. Years later, you have this guy who prides himself the most in being German, hates Slavs (who had been demanding equal rights or indepedence from AH through Hitler's youth), hates multiculturalism, hates aristocrats and really hates the Habsburg monarchy. Where could he get such ideas?
And then there is World War One. Hitler happily convinced himself that the Germans would have won, if it wasn't for those meddling backstabbers back at home, because the war had ended with the Germans still occupying Belgium and northern France, having all but destroyed Russia, and without a single foreign boot on German soil. He could not, however, have seen the home front crumbling, or the German lines rapidly retracting under the pressure of fresh Allied armies and their newly invented tanks because he had been blinded in a gas attack and spent the last month of the war recovering in a military hospital where he was told one day of the capitulation. The result can be seen in his actions in World War II: He thought that once France was defeated (and with Italy by his side) he could just wipe out Russia in a single campaign, and he wouldn't even have to bother with securing peace with the British Empire first. Epic Fail ensued.
That and the trauma from all the battles, including one incident where a British soldier could have killed him but let him go (upon realizing who he had saved, said British soldier tried to return in the army with the hope of correcting the mistake).
Fellow mass murderer and enemy, Joseph Stalin, also had an abusive father. Once he was beaten so badly, he peed blood.
Sexual abuse is one of the factors that can lead to men and women becoming pedophiles, though current evidence suggests that this is a very, very small minority.
Many comedians had it tough growing up.
Drew Carey lost his dad at the age of eight, and was molested by his uncle a year later.
Bernie Mac was raised by a single mom, who died of cancer when he was sixteen.
"Why Does He Do That?" by Lundy Bancroft is about why husbands abuse their wives, the multiple ways they do so, the reasons why women sometimes end up thinking it's their fault and how the wives can get away. When asked why they abuse, relationship abusers said it was because their mother/father/etc. abused them. When the interviewer called BS, telling them they would remember the abuse and not want to inflict it on others, nearly 60% of the abusers fessed up and said that wasn't why they abused.
One theory of Anti-Social Personality Disorder is that usually those who have it did not merely have Abusive Parents; rather, they had Abusive Parents who periodically would make some half-assed and short-lived attempt at discipline or generosity, or pretend that everything was "normal", for example to fool outsiders. Its the chaotic and random hypocrisy of the situation that really set them off, teaching them that punishment is arbitrary, kindness is a mask, reality is a Social DarwinistCrapsack World and other such harmful conceptions that they end up internalising, along with a shortage or total lack of more positive role models.
Psychologist Philip Zimbardo spends most of his book, The Lucifer Effect, talking about what causes good people to turn evil, but punctuates it with reminders that understanding the evil doesn't make the people any less responsible.
Joseph Fritzl. Turns out he hid his daughter and three of her children in his basement in Austria for 24 years because his mother abused him. They were also HIS children. Go ahead and think about that.
In The Salmon of Doubt, Douglas Adams recounts the horrific tale of how he had to wear shorts for the first four weeks of sixth form (having been forced by school regulations to wear them all through prep school, despite having already grown taller than most of the teachers). He says that if he ever "[came] across as a maladjusted, socially isolated, sad, hunched emotional cripple... then it's those four weeks that are to blame".
"It is my personal opinion that lyrics cannot harm anyone. There is no sound you can make with your mouth or word that will come out of your mouth that is so powerful that it will make you go to hell. It's also not going to turn anyone into a 'social liability.' 'Disturbed' people can be set on a 'disturbed' course of action by any kind of stimulus. If they are prone to being antisocial or schizophrenic or whatever, they can be set off by anything, including my tie or your hair or that chair over there." — Frank Zappa
Subverted with Serial Killer Jeffrey Dahmer, who went on record to say that he took full responsibility for his actions and that when he heard people trying to explain his crimes by blaming his parents it actually made him angry because they had nothing to do with it, as much in the dark as anyone.
Jeff Foxworthy, you got your wish!
Another famous serial killer, John Wayne Gacy, may have played this straight. His father was not only domineering and abusive, but frequently humiliated him in front of the neighborhood kids because of his more effeminate interests. It got worse when he tried to engage in more typical boyish behaviors and discovered that he had a debilitating heart condition that prevented him from doing so, making him feel like even more of an outcast. People have theorized that all this may have made him bitter and angry at the world and humanity to the point that he stopped trying to repress his then emerging paraphilic urges. That said, there's no way to tell for sure that he would have ended up differently even if he'd had a normal childhood.
In the memoir Dirty Secret, Jessie Scholl describes her upbringing as the daughter of a hoarder, who neglected her children quite badly. Her mother's childhood was very unhappy, and her abusive father seems so unempathic that it is easy to imagine him having a similarly abusive childhood. When Jessie confronts her mother about her inability to care for her, her mother is very regretful, but is also (almost?) incapable of letting go of what she sees as a joke and what her daughter perceives as abuse (teasing with snakes that Jessie is terrified of).
Sam Vakningives his interesting point of view on the role of abuse in the molding of a malignantly narcissistic personality. This includes taking "a more comprehensive definition of "abuse". "Overweening, smothering, spoiling, overvaluing, and idolising the child – are also forms of parental abuse." Vaknin also quotes Karen Horney in that "the smothered and spoiled child is dehumanised and instrumentalised". Vaknin continues that when "The child is taught to give up on reality and adopt the parental fantasies", "The faculties that are honed by constantly brushing against bruising reality – empathy, compassion, a realistic assessment of one's abilities and limitations, realistic expectations of oneself and of others, personal boundaries, team work, social skills, perseverance and goal-orientation, not to mention the ability to postpone gratification and to work hard to achieve it – are all lacking or missing altogether". The person growing up this way "sees no reason to invest resources in his skills and education, convinced that his inherent genius should suffice", and "feels entitled for merely being, rather than for actually doing (rather as the nobility in days gone by felt entitled not by virtue of its merits but as the inevitable, foreordained outcome of its birth right)".
Aileen Wuornos was abandoned by her mother and father, sexually abused as a child, a mother herself by 15 who never got to see her child after the birth, and then suffered homophobia when she realised she was a lesbian. This explains a lot.
Polish psychologist Alice Miller has often linked the abusive childhood of several celebrities to their own tormented behaviour as adults. This includes both dictators and serial killers, as cultural icons like Friedrich Nietzsche, Buster Keaton and Franz Kafka. It is worth mentioning that Miller didn't actually argue that "people abuse others because they were abused;" her argument was more along the lines of "people abuse others if they were abused and were told it was good for them". In other words, the part that poisons them into abusing others isn't the infliction of pain, but them being asked to deny that pain in favor of the powerful adults they must please. Then, since the passage of time inescapably means they soon become the powerful adults, they use the same rationale their parents did to inflict pain on their kids for their own good; in reality, the real reason is that now that they're grown, they can act out the other end of the one-sided relationship they once were forced to accept.
Also, while it wasn't the primary focus of his work, the mathematician and philosopher Bertrand Russell made a similar argument about parental abusers in "The Conquest of Happiness": there was no "great mystery" as to why parents abused their kids; it was because the parents enjoyed the benefits of having a one-sided power relationship (and by implication, the relief that came with no longer being on the other end). So Russell thought parents were becoming increasingly unhappy in his day because they were being robbed of the benefits of a one-way relationship (and by implication, the fact that since their own children would no longer be required to go through that crucible, their OWN acceptance of their one-sided childhoods was for nothing).
Within Psi, a theory that models human personality and behavior, psychologist Dietrich Dörner argues that the feeling of helplessness under repeated abuse in childhood can lead to a persistent, lifelong state of low "competence". This leads to a constant craving for power, influence or acknowledgement.
One possible way to satisfy this need is the accumulation and abuse of political power, as seen with Hitler or Stalin.
Another strategy can be violence towards weaker persons or animals, for example bullying.
Perfectionism in work and private life can also be a way to restore competence. According to Dörner, Vincent van Gogh is a prominent example.