I prefer the Dad/Daughter route and I am baffled why there are so many out there prefering the Mom/Son route. But that is personal preferences in play there, so I just write down some things about the characters in these two stories.
Father - his main flaw is that he was a workaholic until the strain on family got too great, only one he truly kept "contact" with was the daughter. He is not a cheater at this point of the game, the redhead was before F/M went steady. His second flaw is a prudishness that marks him as Northamerican, but maybe this is a reaction to the fact that the sis-in-law and his daughter give him boners. (wink, not that we see them, but it is implied several times)
When it comes to his relationships, that with his daughter is the tightest and for quite some time. When you play the Dad route it is rather upbeat one too, definitely a contrast to the general dour feeling of most of the game.
Without the deplorable shenigans of Cousin Karen his relationship with the Mom would be mendable too, Mom and Dad still have some feelings for each other, but especially Karen is torpedoing that.
Mother - Her beginning to drink was the final nail in the coffin which Dad´s workaholicness laid down. Prefers the son over the daughter and must have been obvious about it longtime as well for the daughter to develop such a textbook case of Elektra Complex. Actually several times in DF it becomes clear that the Mom cannot see the daughter leaving fast enough, while the son leaving fills her with dread and is extremly happy when he decides to stay in his route.
In relationships, her son comes first, but she still has some feelings for the Dad as well. Despite problematic, her relationship with her sister is better than you would think if you follow a certain path on the son route overhearing some talk.
Daughter - The Brain among the two kids and really attractive. She is the Daddy´s girl and has a textbook case of Elektra Complex. It is hinted more than once that her Dance date is more or less a younger version of the Dad and when her brother goads her about Dad spying on her naked, I would not have been suprised if she would have shocked Bro with answering: "He is allowed to" to shut him up. (Should have been an option in the scene)
In relationships, her Dad comes first, but she has good relations to her brother, her Date and her Aunt as well. Glaringly obvious is a slight dislike of her Cousin (Karen on the other hand actively hates her) and the near non-relationship with her Mom.
Son - No matter where his parents failed, they can only partially be blamed that the Son is such an absolute asshole characterwise and borders on psychotic. I am no specialist on psychology, but have some knowledge and some dialog and interior monlogue show clearly that he is a danger for himself and others.
More in a few days