Most of the offspring who killed their parents, as we have seen, were actually adult children, meaning they were over 18 years of age. Over the 32-year period examined, the number of juvenile parricide offenders was substantially lower. On the average, juveniles killed 31 fathers and 18 mothers per year.
Interesting that it is adult children who are more likely to kill their parents despite more publicity of adolescents killing their parents. Come to think of it, Jack Gilbert Graham, Charles Whitman, Dipendra of Nepal, and Adam Lanza (over 18) killed their mothers before committing mass murder.