This is alleged to be true.
It's parents' evening at a primary school. The headteacher is talking to a single mum who is known to have had many boyfriends, and thus she has many children.
The conversation turns to a particular son of said single mum.
Headteacher: "He's got a fine head of curly, ginger hair, hasn't he? Has his father got a good head of hair, as well?"
Mother: "I don't know. He kept his cap on."