I have a different, complex view on this.
My first point is this: Crime, in and of itself, isn't always morally wrong. Sometimes, committing an act which the government considers a crime, is neither morally negative, nor socially or personally harmful. The crime of treason, for instance, is in my book entirely justified if the motivation is to do away with the immoral practices of the establishment. It would be illegal in America to revolt against the corruption in the police force, for instance, but it would also be morally correct to do so. So, first point established: criminality is not synonymous with immorality.
Second point: nobody is saying that a bad upbringing justifies committing a crime. (although, whether that crime needs justification or not is dependent on whether the act committed is in fact immoral or harmful to society in some way). If I throw a piece of paper on the ground, in many countries that is a crime (littering). However, paper is biodegradable, therefore, throwing paper on the ground is in no way an immoral or harmful act. In my opinion, the fact that it is a crime is a farce.
However, of course, what we seem to be referring to in this opinion poll, rather than petty crime, is more serious crime. And the questions is not "does a bad upbringing justify murder", the question is simply "should a bad upbringing be considered when sentencing criminals".
My view is that, yes, it should. If a society allows parents to behave so lovelessly toward their children that they abandon them for a pitcher of beer, and if that society is content to continue without the correct safeguards in place to either prevent these occurrences, or deal with them in a way that allows mistreated children to regain their sense of dignity, safety, security and warmth, then that society is in my opinion responsible for failing those children. As such, should those children (quite naturally) grow up to have skewed perceptions on the world, with emotional regulation problems and violent tendencies, it is up to the society to take some of the responsibility for allowing that kind of life for the child.
Should such a person be convicted of a criminal offence, it is my view that the sentence should not be a mandate to lock that person away into a violent, rapist atmosphere where their emotional and mental disturbances will only get worse, but rather that the sentence should be a mandate for empathetic, therapeutic treatment over a long period of time.
Mental rehabilitation is impossible where there is violence, rape, drug misuse and isolation. Those are the kinds of things that created these criminals; how can anybody possibly think subjecting them to more of the same will somehow fix them?
Childhood circumstances should have a little sway. There is something to be said about having a bad childhood but there needs to be a limit as to how much influence this has on a courtroom event. Perhaps it should account for 15% of the crime. Murder and what Manson did is so heinous though that it is hard to even imagine allowing this.
If you've murdered someone as Charles Manson did, nothing short of that fact should really be taken into account, as you're a danger to the rest of the society. However, presenting that example here is unfair, because most criminals aren't serial killers. If someone can be reasonably released back into society after doing their time, then their upbringing should absolutely be taken into account, and an effort should be made to rehabilitate them.
Many people have turbulent, abusive or inappropriate upbringings. That does not give them the right to take human lives or commit any other crimes. Therefore, the court system and society should only consider the upbringing a little bit. When they are sentencing someone, they have to look at the person's entire life. Did the person change or eliminate the criminal behavior as he or she matured? Is the person repentant for the crime? Is it likely that the person will repeat the crime if society and the courts do not punish the person harshly? How long ago did the person commit the crime? What were the circumstances surrounding it? The judicial parties must consider all those factors as well as the harsh upbringing. Charles Manson killed many people in the cruelest way possible. I highly doubt that had anything to do with being sold for a pitcher of beer. Furthermore, he was not repentant in the least. We're all vulnerable to sin, but come on.
No, a tumultuous upbringing should not be taken into account when sentencing a criminal. Sentencing should be based on the seriousness of the crime and the perpetrator's current state of mind or at least at the time of the act. If someone is determined to be insane, then their mental health provider should consider the childhood events.
I will admit a bad upbringing can have very bad effects on brain and mind that is obvious but i do not think that is a just reason to commit a crime I think maybe a test should be done to see if they are fit for society or even a jail for that matter