The three sons

[From The Book of Genesis, illustrated by Robert Crumb (New York: Norton, 2009). Click for a larger view.]

In the introduction to this volume, Robert Crumb describes his Genesis as “a straight illustration job, with no intention to ridicule or make visual jokes.” And it is a straight illustration job, a brilliant one. But at least one joke has slipped in. Do you see what I see in the above panel?