How, Or Actually, How Not?

Is it really possible for a parent to favor one of his children over another? I have always heard comments flying around about how they love this kid or that one better, but I have never really thought that it is meant literally and that instead it is more of a perceptual thing conceived by a child who wants to justify their being mad at a parent. I do understand that in animals (other than humans) some favoritism would be visible because of biological factors that will have an effect in survival, such as not feeding the runts or caring more for the strongest individuals of a litter or a nest, as expressed in The Selfish Gene. However it is hard for me to imagine that, say, one of my friends or relatives lives in a house hold where some siblings are more important than others, and even more so that this happened for arbitrary reasons.

In the case of humans I would think that any being that was born in a family that had more children would be well received and treated equally because of all that playing favorites implies. It does not only say that one child is more loved or more appreciated than others, but it also states that the not preferred children are less important for the community. Is it possible, regardless of this, that I do know parents that have favorites? I probably do. My surprise comes not because I condemn the fact but because it makes me curious how houses hold with this certain benefit for some functions well. Is this favoritism obvious and admitted or is it something that is never discussed but still evident? Is it something that a parent decides or does it comes just like that? I guess I would lean more towards the second idea because it is not hard to see how a mother or a father can pick. We are actually taught to pick what we like best since we are small: our favorite color, the ice cream flavor we like the most, the animal we prefer, our best friend, etc. Looking at the evidence it seems as if the small minds of children were being structured to pick the best thing out of the available options all the time, to find something to identify them selves with. The question would then not be how some parents have favorites amongst their children, but more so how they do not. The question I have to ask myself, I notice, is how is it that some parents, most I would even dare to argue, maintain the strong influence of choosing out of their family lives and give all their children equal and unwavering love.