Should a family tree strive to illustrate a biological line? What if you discover that a great-great-great-grandfather was really the illegitimate child of someone else? It was an affair, which meant that his birth certificate lists his father, but only later did he assume his biological father's name? This means that the information isn't found any of the official records.
Which name would you list in the family tree (versus which name is added onto notes)? Would it matter if the biological father was supposed to be noble? The noble aspect makes me more hesitant to add the biological name. Although it would be interesting to find a DNA match that validates the story.
What would you do?