Giving some thought to, say, European history, gives thought to endless wars, plagues and famines. And a generally high mortality rate among both moms and dads. Leaving aside the hanky-panky, there must have been many informal adoptions and second or third marriages. So what's in a name?
Probably the most dramatic, was a little old lady, who new to tracing her ancestry. I found her grandmother listed in the 1880 census as "ad-daughter". Which translated to adopted of course. The lady slung her three ring binder at me, and accused me of lying to her as she stormed out. Bottom line, is if you get into this hobby far enough, I guarantee that there will be at least one bit of unpleasantry (if you are in that frame of mind).
Of the I have much more pleasure of seeing the people who I have helped. I helped one gentleman find his grandfather who he had been searching for off and on during his whole life. His comment was "I am dying of Luekemia, I had given up hope of finding out what happened to him". I teared up, and knew that my help was worthwhile.