In medicine this concept is done time and time again. If you have arthritis, we screen with ANA testing. If the test is negative, we move on as there is a 98% chance you do not have lupus causing your arthritis. Screening for a characteristic you desire (or don't desire) is an acceptable practice, so this is why I see merit to Dr. Mark's idea, and will go to the other end of the spectrum and call it a brilliant idea, just as there was an idea of brilliance in the persons that taught us physicians how to evaluate a patient for arthritis. Anyone with arthritis out there I bet could really appreciate this concept, because I cannot believe such an arthritic person would call their doctor stupid for practicing these same concepts.