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[AmsterdamAssassin]

Many serial killers start out abusing/killing animals as children. When they grow up, they graduate to killing humans instead.

Yes, however I know autistic people also have problems treating animals the way animals want to be treated, which can result in the autistic child hurting the family pet for not acting the way the child wants. Psychopaths don't think animals have feelings. Autists know animals have feelings, but they fail to read the animal correctly and often get angry at the miscommunication.