If you have any history of mental illness or cancer in your family, don't disclose this. You will be blacklisted from ever being able to participate at the clinical research company you were looking to get recruited into.
Yeah, I remember how disappointed the supervisor of the study was that I just didn't mention one thing about my medical past since I was in the final round which means they would have one less participant for this round of the study (no time for new search).
It was a very minor thing and a long time ago, so I tried to explain how it's actually completely irrelevant and then I realized how dumb it was to mention it at all, lol
But since I mentioned it, they had to disqualify me, as much as they wanted me to join. Was a very sad day in my history of being a poor student.