I would think that no matter what you are talking about..if you tell someone that what they have believed all this time is wrong you may deal with thier harsh reaction.
Telling someone " Btw.. 20 yrs ago I adopted you" would get a violent reaction as well. You rock someones world with info they may not be ready to hear or handle.
When my ex-husband starting telling me about holidays ( he was non-jw) and how Jw logic was silly since you can trace pagen origin to almost everything ..etc. I yelled at him and ran to my closet and sat holding my knees rocking back and forth. I felt crazy! I figured he must be evil and trying to lure me away from the "truth".
Then I started hearing the same information from other people and started thinking.. "What if they are right?"