The question does ask whether people have ever given blood, though. You could consider people only among a sufficiently old cohort (so that they would have had a chance to give blood before they would likely have identified as EA), and see if there’s any correlation.
The question does ask whether people have ever given blood, though. You could consider people only among a sufficiently old cohort (so that they would have had a chance to give blood before they would likely have identified as EA), and see if there’s any correlation.