you make some interesting points. I disagree about incest mainly because it would make brother sister relationships difficult if people starting accepting it. I mean one of the reasons they work is because there isn't any confusion with sex and infatation going on in the background. Also you generally spend a lot of time growing up with that person its easy to love them. That's half of love is knowing and understanding them how else would you care for someone. There is more to this but I find it hard to articulate.

I also found your concept of heart interesting I thought of it like how you would think of a soul and how our souls make us different from animals. Like this heart quality is what makes us human. You need to have a personality, identity and morals. You need to seek knowledge and understanding. I know it sounds religious but I really don't mean it in that sense. Its like in order to connect with another human you need human qualities.