Freud? Aiiii spare me. I read The Interpretation of Dreams as a student; what a load of hogwash. He is important insofar as he fathered the entire psychological, psychotherapeutic movement, but the concrete specifics of his theories don't hold up very well.
I watched a documentary some time, which you'd probably find interesting. I think it's this one: http://topdocumentaryfilms.com/biology-of-dads/ but not sure. Youtube is blocked at work so can't check.
My daughters were just like that. At 14 months, their natural instincts are more assertive than learned behaviour or what they glean from their peers. From about 8-9 years old they wanted to bath themselves and choose their own clothes, up to a point. My wife and our daughters are like best friends and have continued into adulthood (they are 33 and 35 now)
my 20 month is the same. changes from day to day as to who to go to. when we go out though she sort of sticks to her mum whereas just before we left she would be with me. i honestly dont get the reasoning but thats what makes them babies i guess..
Normal behaviour for children. Sometimes the favouritism is brief, other times it lasts longer. It doesn't mean anything.