this isn't just about them preferring ONE parent over the other....you have to remember these are children of an alcoholic, they have been raised under a different and dysfunctional set of rules in a life full of lies, abandonment, fear, insecurity, drunken displays, anger, all under the pretense of NORMAL. they are driven by a lot of psychological factors they could not begin to name.
this is really interesting, albeit a bit technical article that you may find helpful
Delaying the Crossroads: The Impact of Parental
Alcoholism on Self-Authorship
http://education.indiana.edu/graduat...Crossroads.pdf