These are rare but real situations. All of these are excellent reasons for knowing who your biological parents are. Now let's examine kabud av v'aym. Jewish tradition teaches that the adoptive parent is to be praised. However, according to Halakha, adoption does not constitute a blood relationship.
Jewish law focuses entirely on natural relationships to establish parental rights and duties.
From the halakhic sources I've seen, you would not be breaking the mitzvah of kabud av v'aym, by looking for your biological parents. However, the way you go about it will make all the difference in the world in your relationship with them. You can show respect for your adoptive parents by honestly, sensitively discussing your feelings with them first. If your current relationship with them is shaky, perhaps there is a trusted family friend or your rabbi who can be there with you when you begin the discussion. And trust the love that brought you and your mom and dad together.