Families are systems where no one is isolated from anyone else. If one person is like a bent cog, then they may choose to marry someone else who is damaged, and then the children have to adapt to this wacky environment too.
There is a “dysfunctional person” like Homer… often an active addict or someone with an untreated personality disorder. They marry an “enabler” who is like Marge – endlessly trying to make everything right. The enabler thinks that the dysfunctional person’s problem is their responsibility. Ironically, so does the dysfunctional person.
The oldest child becomes the HERO, like Lisa. They try to make everything in their family ‘better’, and the task is completely beyond them. They cover up feelings of inadequacy by overachieving and people pleasing. The stress and responsibility of their role is incredible. This child usually grows up to become an enabler and co-dependent. They slowly learn to put their needs last and their life on hold for others.
The second child becomes the SCAPEGOAT, like Bart. Challenging the dysfunctional person is counterproductive and so everyone in the family vent their frustrations on the scapegoat instead.
Another child may become the LOST CHILD, like the baby Maggie.. who broadly doesn’t draw any attention and doesn’t cause any problems.
Obviously, lots of generalisations in this, but I read a scholarly tome by Dr Robert Skynner (of Families and How to survive them fame):
..and in many of the detailed case studies the children were acting in these roles in order to survive family life!
Simpsons is scarily brilliant at highlighting the internal workings of a dysfunctional family!