The Bell Cannot Be Unrung

My Christmas present this year was a genetic phenotyping kit from 23andme. Before you do anything, they recommend that you register your kit (submit your name and a barcode number on the test tube you receive). Part of their terms of service:

You may learn information about yourself that you do not anticipate. Once you obtain your genetic information, the knowledge is irrevocable.

I wonder what kind of drama has happened that they felt the need to include something like this in their TOS.