Take a bird couple. They end up having 4 chicks. If there’s just the two parent birds, perhaps 2 of the chicks survive. Each of the surviving chicks carry 1/2 of a parent’s genes, so each bird only passes down his or her genes x1.
Now, let’s say the 4 chicks have a gay uncle bird that helps out with food gathering and defense. All of the 4 chicks survive. Each of the parent bird now passes down genes x 2. Even the gay uncle bird indirectly will pass down his genes x1.
