Sometimes you may want to find all such "problem children": 

If I understand your problem correctly, you want a list of individuals whose parental relationship is not "natural"? 

This is easily accomplished with a Custom Report. Make sure you include item "Parental Relationship (adopted...)" in the report so you can "see" the relationships. Then include individuals where this field has a value "Not Natural". 

Be forewarned: Sometimes an individual will appear in this report, but the displayed relationships will be "Natural Father, Natural Mother". You will find that those individuals have more than one set of parents (but only the "preferred" checked one is listed). Get to a Family Page where that individual appears as a child. Select him/her, Click People/Other Parents to see (and select) the other set(s) of parents. The abbreviations after each parent indicate the relationship: N=Natural, A=Adopted, U=Unknown, &c &c