The categorization was the result of years of study of the best practices of information organization augmented by anthropological research into the importance of interpersonal relationships to parenting.
Actually, I just didn't think that a "Moms and Dads" website should have a "Parenting Discussion" category that was significantly smaller than the non-parenting category. So, I padded it with the relationship forums. Since then, I've added more forums to the Parenting Discussion and the padding is no longer as necessary. I've also added more non-parenting forum and that category is rather large now. If anyone has ideas for a new arrangement that might involve an additional category, I'm all ears.