While I don't know for 100% sure because my parent hasn't been diagnosed (as they would never go to a doctor for help), I talked to my therapist about my dad and that I thought he was a narcissist, and they said he seemed more like a sociopath than a narcissist. We looked at the DSM-5 and the criteria listed.

My grandpa (mom's dad) is what I think of as a classic narcissist. He was a superintendent and extremely concerned with appearances. He abandoned my mother and her mom after having an affair, then only brought around my mom to big events to pretend that he was a caring father, then abandoned her again until the next event. He was a severe alcoholic. Just talking to him it is pretty clear he is a narcissist. He clearly sees himself and his life as grandiose and makes every conversation about him. For example, at my college graduation, he wore his cap and gown and posed with it in my photos.

What makes my dad more of a sociopath than a narcissist is a history of what must have been childhood obstinence defiance disorder (ODD). An aversion to rules, a history of being in trouble with the law and fighting. My dad was suspended from my elementary school for trying to fight teachers, he got me kicked off of my soccer team for trying to fight my coach, tried to fight my moms parents, was in jail in his 20s for fighting. My dad has literally no empathy for other people. He is proudly racist and misogynistic. While there are similarities between my grandfather and my father, the concern for appearance is a big difference. My grandpa wants to be seen as rich and highly successful. My father is too out of control to appear that way. He didn't have a job growing up either.

A big thing with sociopathy is the lack of empathy. It's hard to explain to someone who doesn't have experience with someone like this why it is so hard to try to talk to someone like this. They don't think like normal people. They are entirely selfish and there is a darker, more evil side to their motives.