14.8

That's the number of years that the wife should be younger than the husband to maximize the number of living offsprings to reach 18 years. This is Scientific American speaking, man, not FHM or Playboy. So our 1/2 plus 7 rule is even conservative. More details. The study was done in Sweden over two centuries. You can not dispute that! Purists, however, may say that the study was made on one group in Sweden and the records were culled from 16th and 17th century but who cares? He he he