i dot think that is a beneficial reason...i mean if richard hawking's dad thought i carry the gene for xyz, that woudlnt have benefited the species...right? not to say i am pro life, but in this case i don think you are the one who gets to decide which genes are important enough to pass on. you could be caring a gene that makes us resistant to some future strand of ebola or something.

as far as the reason, its genetic. everything we are is in one way or another to preserve our genes. sharing resources, in any case, is only beneficial when it makes the likelihood of our genes survival more probable. so fear is an instinct that we might not have such a need for living in america suburbia, but we had much need for it 10000 years ago. and it has not faded. as with other genes that were present because they evolved to be dominant, they have kept themselves that way. so sexual desires and fear still dominate our actions. the issue and the confusion comes, in my opinion, when these genetic dominant traits dont line up with todays culture. becasue our genes say, dont share resources, but society sais...share away, its sinful not to. yes?