There have been models that pretty convincingly show altruism arising without any special prerequisites. It's basically a balance between propagating directly versus ensuring propagation of enough of your kin. They may even be very distant kin, not sharing that many genes with you - but if your altruism helps sufficiently many by sufficiently much, you end up propagating those shared genes more successfully, in a sense of having more carriers of them in the follow-up generations. And if those shared genes include the ones that affected your altruistic behavior - again, in at least some of those you helped, not necessarily all - then it becomes a selectable trait.