It is common knowledge that there is an instinct which drives parents to care for their young. From evolutionary standpoint it is explained by the fact that parents are trying to make sure that their genes survive in their offspring. This same reasoning can be used to explain why people care about their brothers and sisters and the rest of their kin.
Of course, if we were to ask a parent why they care for their child they would not say "because I am protecting my genes", rather they would say something along the lines of "What do you mean "why"? Its my baby and I love it!"
So in this case, we are not motivated to behave in a certain way by evolutionary implications of our behavior, rather we are governed by an immediate instinct. From what I know that such a behavior would have to be genetic in nature, as opposed to being learned, much like eating when hungry. After all, a mother doesn't need to learn that caring for her child is the thing to do, she simply acts according to her instinct.
My question is how did this instinct come to be? Was there a time in evolution, when organisms didn't have this instinct? Would an organism X number of years ago not have an instinct to protect its offspring? Was it that at one point a mutation occurred which made organisms care for their offspring and this behavior made the organism so overwhelmingly more successful at making sure its genes survive that it quickly muscled out all other organisms that didn't have this instinct? Or was this instinct present from the very beginning. Did the very first cell ever to reproduce have an instinct to protect its offspring?