At two points in the game, glitches allow you to disrupt the family line through unnatural means. Early in the game, Rhys will be thrown into a dungeon. Normally, there's no way to escape without meeting Lena and advancing the story, but it is possible to sell the Boots he is equipped with and buy an Escapipe with which you can warp out. Try this, and the king will tell you that the game can't continue! You have to know these things when you're king, you know. Of course, if Rhys doesn't have to meet other characters to escape the dungeon, he'll never get married in the game's narrative and there won't be any more generations (of doom). It is, however, actually possible to rejoin the game after breaking continuity like this, using more glitches.
Even stranger is the ability to skip a generation entirely, going straight from Rhys's story to Aron's. It doesn't change the characters' lineage, it simply jumps over Nial's entire storyline. Aron will then have to go back and play some of Nial's quest, despite being in a different time period.
This trick also requires an Escapipe. Give one to Wren or Mieu (ageless cyborgs who follow you across generations) before the last boss fight in Rhys's generation; after beating the boss, choose to marry Lena. As soon as you regain control of your character, use the Escapipe. You'll then play briefly as Nial. You'll have to fight the boss again, at which point you can choose to marry Alair and skip forward to Aron's quest.