Allie can't have any more babies, even though she and husband John would like another. In a moment of delight as he fills her pussy, she has the idea of getting her son to fuck her eldest daughter pregnant. Perhaps, she reasons, if she were to get him addicted to bareback sex and then somehow contrived to get him up close and personal with Danni, maybe nature would take its course? There's another member of the family, Rachel, who hasn't yet reached menarche, as far as anyone knows...
A bent cock gets experimental medical treatment that makes life much more interesting for our hero. Not only is the crooked made straight, but the "road" gets lengthened and thickened in the process. ...and when you get a gift like that, it's important to share it with the everyone else...
A father, me, and son, Barney, have to get across to daughter/sister, Midge, the dangers awaiting young girls when they want to start dating. Their warnings must be effective, because young Midge never does go out with the young man she originally fancied, preferring to stay home, where Barney and I drive home the lesson - time after time. You could say, she gets the point.