Whether or not you are convinced that the Westermarck effect is real, I seem to remember that there were a few cases of genetic siblings or half-siblings reared apart who later met by chance and found themselves powerfully attracted to each other, whether by elements of physical resemblance or vocal patterns or philosophical outlook. A good case for adopted persons being able to run at least blind checks on parentage before pairing off.
That said, I would love to have a secret twin—even an unrelated one—and I have always felt the absence of the female miscarried fetus who came and went precisely between my strange and difficult brother and me.
@4 Two parents have a 1in 80 trillion chance of creating identical twins on each separate kid (barring any genetic mutations) and they are using identical dna going into each of them. Odds are low.
Who knows...maybe even DNA has its limitations...starts repeating itself.
There are 6 or 7 billion of us wandering around.
You can't be original every day.
That said, I would love to have a secret twin—even an unrelated one—and I have always felt the absence of the female miscarried fetus who came and went precisely between my strange and difficult brother and me.