Is it considered a sin not to change a birth certificate from the adoptive father's name to the biological father's name, taking into account the psychological and social ramifications for all parties?

What your father's uncle did by attributing your lineage to himself and adopting you is a haram lie, unless it is out of necessity, such as being compelled to stay with him during his travels to save you from ruin and perdition. In such a case, his action is permissible, and you will be rewarded for it. However, as soon as the necessity ceases, matters must be returned to their true state by restoring your lineage to your real father and immediately removing you from the adopter's documents, because a child being attributed to other than his father is haram, and to preserve lineages from mixing and loss. You must change your official documents from your father's uncle's name to your father's, and inform your father's uncle that this is the sharia ruling. We also caution you that this man's wife is not one of your mahrams, so it is not permissible for you to be alone with her or to see her except with her legal hijab.