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In which scenario is this possible?

  1. Jul 4, 2007 #1
    Here is a little brain teaser:

    You are my brother, and your mother is my mother. However, your father is my son's brother. If no incest occurred, how is that situation possible?
  2. jcsd
  3. Jul 5, 2007 #2
    First off, by "brother" you have to mean "half-brother" in at least one, if not both uses of the word. So, because it must mean "half-brother" in at least one, since your wording affords no difference between the two, then BOTH may be half brothers, making the problem trivial.


    "MY MOTHER" and "MY FATHER" have a child, which is "ME".

    "ME" and Pat have a child, "MY SON".

    Pat and Terry have a child, "YOUR FATHER"

    "YOUR FATHER" and "MY MOTHER" have a child, "YOU".

  4. Jul 5, 2007 #3
    You are correct. It has to be assumed that they are half-brothers though since if they were real brothers it would make the scenario impossible.
  5. Jul 5, 2007 #4


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    I was wondering along those lines too, but it stretches my idea of a "valid" teaser, because the trick to it is so obvious while at the same time rendering the problem trivial.
  6. Jul 5, 2007 #5
    All questions are trivial when you know an absolute answer.

    What interests me is seeing a grey one though, food for thought, like "Einstein's" riddle.
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