causality. We don't know the order of events or the mechanisms. Leaping to "must be the result of damage" just reinforces the "INFPs are broken" meme, which some of us absorbed from external sources in childhood (even if we didn't know we were INFPs). So you may get some prickly responses.
As a gay man I react with similar hostility to "being gay is caused by family damage" for the same reasons. Self-worth and sane thinking are an uphill battle when you absorbed messages that who you are is broken. It's interesting that even though the most recent research indicates that genetics and hormone levels in the womb are the biggest factors in determining male homosexuality, you still often hear theories of family dynamics and improper parenting trotted out.
So, I'm happy to talk about the strengths and weaknesses of being INFP (or being gay, for that matter), but I'm unlikely to go along with "being INFP is the result of damage" without some pretty strong evidence (correlation and time order, at the very least).
As far as INFP conflicts between fathers and sons, in particular, it seems likely to me that some fathers may find relating to INFP sons a little difficult. INFP women aren't stereotypical women either. They are too introverted, not into the Fe thing, etc., so those traits could sometimes lead to strained family dynamics, as well.
Plus, as INFPs we have the added bonus of being very aware of every negative reaction; it's harder for us to turn off our perceptions of the emotions of others than it is for some other types. I could see that dynamic leaded to more reinforcement, since subtle reactions happen more often the explicit negative statements.