It is exacerbated by our current system for sure but I think the core of it is still there, genetically. I say that because I remember my old dog would act up i

It is exacerbated by our current system for sure but I think the core of it is still there, genetically. I say that because I remember my old dog would act up if I petted the cat sometimes. Also very young toddlers show envious behaviour when a sibling is born.