Regarding the boy/blue cards I can hear what you are saying about destroying them and on one level I agree. However as a Libran, I am either blessed or cursed, with the dilemma of seeing two sides of the coin.
Fast forward 40 years, the time when many human beings become really interested in family trees, interrelationships with cousins and broader 'family', and as a result discovering more of their own story within that context.
In my search for early information about myself while putting my CAH story together, after a lifetime of silence, I jumped at any piece of information I could glean. I was an adult (hopefully a well balanced one albeit), I knew who I was and felt comfortable with who I was, but some information was missing. As I found each piece of information I digested it, sometimes with tears, sometimes with misgivings but in the end it was my story. I would have been angry if I had found out that some pieces of information had been deliberately concealed.
It's a bit like adoption - what information do you keep from the child? Conception by rape/incest- almost certainly. But what information is the adopted adult entitled to know or have access to. The child and the adult - two different ages and stages?
So the question is, do we have the right to know everything about ourselves as much as is able to be known and discoverable, or should some things be suppressed in our own best interest?
Ask a psychologist, or better still several psychologists, to get a consensus.