When Six explains his backstory to Miranda, he notes that he thought the killing of his father to protect his little brother was "noble". But he follows that up with "everyone else thought I should be in jail". Considering the sentence he got (incarcerated in 1995 at age 15 and not eligible for parole until 2031) this means that not only did his mother and brother keep quiet about the abuse suffered under Six's tyrant of a father (which would have at least given Six some mitigating circumstances due to the defense of a third party) but they must have actually testified against him to give him a longer sentence. To go through the horrific abuse he did, kill his abuser, and then have his family turn on him and send him to prison, it's no wonder why Six agreed to have his identity erased.
