7 year old pooping in pants

Our 7 yr old girl started pooping in her pants about a month ago. We have tried all forms of discipline with no success. This seems to be timed with a project at school discussing their family tree!! We were forced to discuss with her that she was adopted before we felt she was ready!!! It may be a coincidence but we're not sure. At any rate we don't know what to do. Any comments would be greatly appreciated. Thanks Cindy