The Cousin Tree

Here's an image taken from Wikimedia that shows the degree of genetic kinship between different family members. The more closely related two individuals are, the more likely they are to help one another out, even at the expense of their own "fitness." (The geneticist J.B.S. Haldane said "I'd lay down my life for 2 brothers or 8 cousins," illustrating this point.) This is called kin altruism, which is a behavior that comes under kin selection.  I thought this tree might be interesting as we read about altruism, even though The Origins of Virtue is largely about reciprocal altruism, not kin altruism.