I am an advocate of sharing the information about adoption with the adopted children. I believe very strongly in this because the information belongs to the child and secondly it is a betrayal of trust.
Having said that, I know there are families out there that believe very strongly in contrary to my belief system. I don’t say they are ‘wrong’ but their line of thinking is not in the best interest of the child. If a family is just not willing to consider others point of view I want them to be aware of most possible places where their child might hear about their own adoption.
Friends & relatives: Your legal adoption couldn’t have taken place without someone (like friends and relatives) knowing about it. From there, it spreads to others and especially if it happens to be children, it cannot be a secret for very long.
School: If one child from above situation (friends & relatives) happens to be in your child’s school, you can be assured that it spread to the entire school like wild fire.
Doctor’s visit: During your child’s doctor’s visit, you might be asked about the family history, pre-existing conditions and blood group matching that could spill the beans.
In conclusion, in each of the above situations, one could come up with a compromise such as not visiting the relatives, moving to a new town/ city for school or simply cooking up a story to a doctor, consider the costs and effort that one has to put in to keep a secret.
Even those that talk openly about adoption with their children need to be aware of these possible places to ensure that they don't affect the child adversely in anyway (for example bullying by kids at the school).
In spite of all your efforts to keep it secret, if the child does come to know about adoption from someone else, will the child respect your way of handling his/ her story of adoption? Time will tell.