Hermes,
Karma, good as well as bad, is spread around, with each person receiving their fair share of good/bad karma for the good deeds that happen. If a father is mean to his child and raises his child to be a bad person, and that son then goes out and commits a crime, both the father and the son will receive bad karma from the committing of the crime.
You said,
"…some personality disorders can cause the person to be a liar, for example. Is that the same karmic weight as a "normal" person who lies for a malicious reason (just to turn back to the philosophical/spiritual mindset....)"
--> Yes, all of these things are separated out into mitigating circumstances. To the extent that a person is helplessly motivated by a bad upbringing, he/she does not receive the total amount of bad karma from doing a bad thing. But if the person has a sense or right and wrong, they will receive an amount of bad karma relative to how well they should have tried to prevent themselves from doing the bad thing. It is all relative, and bad karma is dished out in a relative way.
"…these are all mitigating factors, thus the karmic record-keeping (akasha) has to do some post supercomputer, matrix like balancing and re-balancing…"
--> Yes, that’s right. Just recently, in the news, I heard about a young man who went to a school and killed several people. But from hearing more details about the case, I am quite sure the father is guilty of having raised his son in a very bad way, and I am convinced the father will receive some of the bad karma from the killings. American civil law does not hold the parents of such criminals accountable (which it should) but karma does.