In the realm of human possibilities, you could probably find cases of both in addition to cases where the bond with the father is fine but something else, such as sexual molestation by a homosexual, has caused the problem. The researchers describe an observed pattern. Humans are far to complex to have their psyches reduced to a collection of cause-and-effect resonses.
The important thing is that they are finding ways to move the sexual identity back to the norm. That's what the pro-homosexual cheerleaders truly hate.
So, absent any evidence, we slap the kid into therapy and tell him how screwed up he is -- a 5 year-old kid -- and tell the family how rotten the parents are?