There is an interesting but very short article in the science section of today's NY Times (it's Science Tuesday!) about the claim that twins can run in families but they skip a generation. The bottom line: twins can run in families but not necessarily skip a generation.
In my family, they have skipped 3 generations. On my father's side, my grandmother had twin sisters (Ruby and Ruth) and my grandfather had twin brothers (Ray and Roy). I have no idea why names starting with "R" were so popular 100 years ago, but I digress. There are more twin sets in my family (all on my father's side, BTW) but they've skipped 3 generations.
And naturally, the writer of this piece, Anahad O'Connor, uses the concept of myth in the Platonic way: "The notion that twins always skip a generation is also a myth." It would actually be a full-time job to try to correct this misuse of the word "myth" in the press, but it still makes me cringe.
Also strange is the illustration just below the large block words "THE FACTS" -- well, THE FACTS ARE that kids don't grow on trees, to be plucked from a branch like fruit. Creepy.