Consider:

“Before anyone else posts a comment insisting that it’s mathematically impossible for any individual to have an unequal number of male and female ancestors, consider the following Edenic scenario. There are two women (Ginger and Mary Ann) and two men (Gilligan and the Professor) on a deserted island. Both women spurn Gilligan and have a child with the Professor. Ginger has a boy named Gino; Mary Ann has a girl named Maria. When they grow up, Gino and Maria have a child. This child will have three female ancestors (Maria, Ginger and Mary Ann) but only two male ancestors (Gino and the Professor).”

“If you think this is a bad example because it involves a half-brother marrying a half-sister, suppose that just as Gino and Maria come of age, they discover another clan living on the remote East Side side of the island. East meets West, and Gino and Maria each marries an East Sider. But their children will still have fewer male than female ancestors in the West Side portion of their family tree. And if the East Siders have a similar social structure — one alpha male grandfather who impregnated all the women on the East Side — then the children of Gino and Maria will have fewer male ancestors in both sides of their lineage.”