# Answer to Puzzle #50: Brothers And Sisters I Have None

50. A man is looking at a photograph of someone. His friend asks who it is.
The man replies, 'Brothers and sisters, I have none. But that man's father is my father's son'.
Who is in the photograph?

Another very popular puzzle, which I think it's about time we included. Perhaps we can find a better way of explaining it:

Let's break the puzzle down in to smaller pieces and then put them together and see what we've got. 'My father's son.' We'll draw a diagram from the perspective of the person speaking.

My Father's son is my sibling.

'That man's Father' appears in our diagram already, we know him as My Father's son. They are the same remember that man's father is my father's son'

'Brothers And Sisters I Have None' - thus far we have identified My Father's Son and Me as separate people. But if I have no brothers or sisters then my father's son can only be me.

Or just...

To clarify 'That Man' is my son. If I have no brothers and sisters then my father's son can only be me. Which means I (me) am that man's father.

As you'd expect both AI's got this correct. It is, after all, a classic.

If you're curious what Bard made of this puzzle...

If you're curious what ChatGPT made of this puzzle...

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