I have it, my husband has it, my sister's oldest son has it and I am pretty sure my third daughter does as she is JUST LIKE ME, and I am thinkin my second may also as she processes information similarly.
HOWEVER - none of us is/was EVER a discipline problem.
I do agree that too many people use this as an excuse for poor parenting.
People with ADD or ADHD are more intelligent and require more mental stimulation because they bore easily. It is NOT a bad thing IMHO, it is actually a gift as it helps you to do more than one task at a time. But you need only be aware you have these issues and know that you must either REALLY focus on something you find to be painfully boring or YOU WILL screw it up. LOL
As for not being able to behave - that is utter bunk.
Granted neither my husband or I or any of the other members of my family who are this way are *average* in many regards, but why would we WANT that?