Are there exceptions to inheritance laws concerning the right of adopted children to inherit from birthparent relatives?

Question Details:

My aunt died and left a small trust to the grandchildren of my mother and father (specifically named). I have 1 son who was adopted out but reunited with his birth family once he was an adult. This aunt set aside a trust for all grandchildren of my parents none of whom (grandchildren) were named specifically within the Will. During the process and distribution, my son was denied a portion based on his having been adopted out, though my relatives had welcomed him back. This denial is resulting in family conflict and I would like to see it resolved fairly. Does he retain any rights in this? Important Notice