This reminds me of a story my dad told me about an ex-girlfriend of his in Sydney
She was a primary school teacher, and one day in class she was talking about parents, inheritance and general pre-Birds and the Bees type stuff. Apparently she said to her class;
Her: Hands up everybody who looks like their mum!
..Some kids raise their hands
Her: Ok, hands up everybody who looks like their dad!
Her: Right, hands up everyone who looks like their Postman..