OK, so this story of twins marrying twins and having twins is fun but…
Soon afterwards, despite a million-to-one odds, Diane and Craig went on to have identical twins of their own – Colby and Brady, now seven.
Odds of monozygotic twins are some three in a thousand. So the odds of this couple having such is indeed three in a thousand. The one in a million might be reached by counting the odds of the parents being twins, but as that had already happened that doesn\’t influence the odds of their having twins themselves.
When actually checking these numbers I was a little surprised to see that monozygotic twins are not thought to be influenced by genes (unlike non-identical such) but that i in a million is wrong all the same.