left I've seen this type of behaviour occurring in a 'together' family unit within our own family, so it's not always a step family situation.
I want to caveat that this is just from my own observation in this particular situation, not any research!
The long term impacts have been different for all those involved (I've seen it over a ten year period so from mid teens to mid twenties).
From the daughters perspective the lack of boundaries seems to have contributed to anti social behaviour (criminal proceedings for violence not chewing with your mouth open) Arguably this could of happened without any spousification but I think that the lack of boundaries in childhood has led to a disregard for consequences in adult life. Just my opinion.
Lack of confidence (no drive to establish independence) so no plans at all to leave home.
Poor academic performance, so minimal prospects for career.
Still very dependant on dad emotionally, financially and domestically.
Strained marriage, unhappy domestic situation. Family still living together so an awkward situation.
A lot of guilt on dads part (which he has expressed but no change in behaviour).
Very, very sad as girl in question was lovely underneath but you could see damage being done.
Family members tried to speak to the dad but he ignored it all.
It was very uncomfortable to witness, dad and daughter were a tight knit couple that used to gang up on the mother in public so not sure what happened in private.
If the dad expressed any wish to spend even a small amount of time with anyone else (DH in this case) daughter would throw a jealous tantrum. I kid you not I have witnessed it! DH was opened mouthed!
It's a sad situation really that has caused pain all round.
Personally I think it's a form of emotional abuse on the part of the parent and not at all the fault of the child. The child is taking their lead from the adult. I personally place the blame for all this at the fathers door.
I think it's an emotive step parent issue because it's the dad at fault not the step child. But its easier to blame the child
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