The odds of any two adults on the planet getting together are about 900 quadrillion to one, author David Bodanis reports, but human mates have a number of inexplicably similar characteristics. In his book, The Secret Family, he says:
- Eye color matches in married couples more than it would in random strangers; so do the lengths of arms and the length of ear lobes;
- The numbers of brothers and sisters of each matches more closely than by chance, as do political opinions and the amount of education each of the couples' fathers has.
A major exception, Bodanis says, is people with red hair -- who seem to hate marrying each other far more than chance would suggest.