First--you are assuming this young woman does not know she is adopted---and yet the only "proof" you have of this is that they deleted facebook when he tracked htem down there and send messages.
Maybe she knows she is adopted and has said she has no desire to meet her biological father and they are protecting her from someone who is trying to push his way into her life now. That is just as plausible really---probably more so; I do not think it is all that common these days to not tell someone they are adopted.
Heck, from how I read things, you do not even know if she has other parents she thinks are her bio parents or thinks of as parents at all---maybe she grew up knowing she is being raised by her grandparents with some help from her very young mother. Again, at least as plausible as the idea that she believes her (grandpaernts? Bio mom plus some other man? who exactly?) are her bio parents.
And, no, I don't think "truth" in and of itself, for no real reason, is always some great thing that must be stated. No one NEEDS to be told when they look like crap for example. I think someone who does not even know the young woman has no right whatsoever to decide what she should or should not know, and I think that if it were me and someone approached me and told me my parents had been "living a lie" and were not really my parents i would be pissed off and hurt and angry, primarily at the person who felt it necesary to decide for me, withizut even knowing me, what i should no---and possibly some at my parents as well (and by that I mean the people who raised me--those are parents) for how they handled things---but honestly, I had awesome parents; if I learned today that they were not biologically my parents i would wonder why they made the choice not to tell me, but I would assume they thought they were doing the right hting beucase I know they love me, so I wouldn't be upset with them in any long term way.
