Maryz, that was an interesting post and I went away to think about it. I think I actually consider looking after my existing four kids as an ethical job in the main, which is probably why I don't get particularly guilty or stressed about my parenting, like some on here.
I often tell them my job is to bring them up to be happy, functional adults and that means sometimes I will be getting them to do some things that they will temporarily hate me for, for example insisting on good nutrition, manners, homework, hygiene and getting up in the morning. I often find myself saying that I am not here to be liked, but here to bring them up well. They actually see the point of this, and I would say we're probably closer as a family than some of their friends' families are. There is certainly a lot of love in this house, but I can't say we have ever chased it.
I don't put a whole load of emotional energy into building love, and a 'normal' family life, because my priorities lie in getting the most number of people feeling happy and fulfilled most of the time. If you get that right, then love often follows. If it doesn't, then at least your conscience is clear. You can't expect kids to feel love or gratitude simply because you have brought them into the world (which was generally your choice, not theirs), but you can do right by them and set an example of being a decent person, which I think is more important. In that sense, I suppose it's what the Greeks would have called 'caritas' as one form of love - altruistic love for a fellow man.
I remember watching a programme on teens in care a few months ago, and there was one kid kicking off and attacking a carer's car. The carer drove away expressing disquiet as he felt he had been working with this teen for a long time, and he felt the teen ought to be more "grateful" and less violent towards him. Surprisingly, I found I was entirely with the teen on this - yet another person disappearing off in his life, a life he wouldn't have chosen for himself, as none of us would. If the carer had worked out that nobody should have to be grateful in that position, that the teen would not have chosed this life for himself where gratitude was expected all the time in return for basic human needs being met, then I think I would have had more sympathy. But the carer just left, and the teen was abandoned yet again.
My point it that sometimes it's more important to be decent than to love. Or perhaps simple, plain decency is a form of love we don't value highly enough.