How do our similarities and differences affect our relationships?

My husband and I recently watched a TV series about a sociopath. We looked up the distinction between a sociopath and a psychopath. One source tells us that a psychopath has no conscience, while a sociopath has a weak conscience. I don’t find this particularly enlightening, but it does suggest the notion that conscience is, like many conditions, a spectrum.
            When I was eight, I was baptized for the remission of my sins. When I was in my thirties, I was baptized again in case I didn’t know what I was doing the first time. But, looking back to remorse I experienced as a young child, I’m pretty sure I knew right from wrong at a very early age. Doesn’t everyone?
            We’re not all the same, though we are also all the same in so many ways. We have a tendency to expect others to react as we would in a particular situation. And sometimes they do, which reinforces the notion of sameness. But sometimes they don’t, and we’re stunned, or at least surprised. When we get to know someone intimately—a spouse, a child, a parent—if we have an open mind, we grow to understand those differences, to expect them. Yet not always. We still find ourselves surprised on occasion.
            I remember reading Little Women for the first time and being heartbroken by Jo’s rejection of Laurie. “We’re too much the same,” she said, or something to that effect. Having married someone very different from me, I understand what she meant, though I still wonder on occasion. Are we better off, or worse off, when we’re quite similar? We know the adage: opposites attract, but does that lead to a happy forever? Does anything?
            In my family, I’ve seen plenty of evidence to the contrary. After being married for well over fifty years, my parents continued to try to change each other to be more like themselves. Did this spring from excessive narcissism, or from a lack of understanding? Both, perhaps, or the former in my mother’s case and the latter in my father’s, though I really don’t know.
            Among my earliest memories are those of my parents fighting. Verbal fights mainly, with insults being hurled freely, which occasionally became physical for a moment with my mother striking out and my dad defending himself. Into their eighties, they would visit me and the quarrels would resume. Were they oblivious to my presence, I’d wonder, or did they prefer an audience?
            I think of my Uncle Prentice, who has witnessed plenty of their spats, and who is known for his clever country saying. One of them comes to mind: That’s why we have chocolate and vanilla.