Honestly I never really loved my parents. My father was a sociopath. He wasn't abusive towards me, but I always knew what he was, even when I couldn't have put it into words. I cut all contact with him as soon as I could. I don't think I ever really even thought of him as a father, not even as a little kid, he was just that thing that was to be avoided. Luckily he saw that I saw what he was quite early on, and he mostly stayed out of my way from that point.
My mother was just a very messed up person. She'd have said she loved me, that I was her world, and that was probably true, but it was always just something said, never something that came through in her actions. She was very anxious, always extremely stressed out even when everything was fine, and she could be very mean and rude. I was always on edge when I was around her. She made her own life miserable and dragged me down with her for years. I hated her at times. The most positive feeling I ever had towards her is pity.
On top of their personal faults, they were just terrible parents. Every decision they made seemed designed to set me up for failure. I don't think they were actually trying to do that (my father certainly might have done just for kicks, but I don't think he was interested enough to bother), but they weren't really trying not to either. I wasn't even an afterthought, I just didn't factor in at all, they did what suited them.
Love has always been a rational emotion for me. I love people because of how they treat me, not because it's expected. I've never really understood how people can love people who don't treat them well, or love people just because of what they signify and not who they are. If I don't like someone as a person I certainly can't love them.