I wouldn't worry about your brother unless his perfectionism is like, interfering with his work, social life, or personal safety (?). As for yourself, maybe your ADD went away (?), you were able to manage it w/o drugs, or you never had it in the first place.
Everything to do with mental health is fuzzy as hell. If you've ever looked at the DSM, you'll know that by and large, it's a conglomeration of vague and overlapping symptoms that apply to like 80% of the conditions out there. Not to say that psychiatry is bogus, but the nature of the mind pretty much precludes any easy way to definitively diagnose stuff. I mean, pretty much everything varies on a continuum. Where do you draw the line between very imaginative and psychotic? What about similar conditions? Extreme cases are easy, so there's obvious differences between your average normal person and someone out of touch with reality, but cases in between are problematic. At younger ages (<10yrs or so I think) for ADD specifically, it gets pretty hard to distinguish between bouncy hyper kid and ADD, so that's also not in the doctor's favor, and lots argue that no diagnoses should be made until they mature a bit more.
I've also heard stories about doctors who'll diagnose a young kid with ADD simply to get a badgering pair of parents off their ass, but yeah. That's like, not standard care, thankfully.