You might want to pause that game, and possibly back up your savegame files, so that you have some options. You may have encountered a bug that affects versions earlier than 1.00.04, and it would be a shame to have a family ended in the fifth generation. The new Mac version will be available very soon, at which point you can resume play and hopefully get at least one heir.

To back up your savegame files, just follow the procedure in this post. Good luck.