Adhd is what is considered a spectrum disorder. It is diagnosed by comparing the child's symptoms (behaviors) against other children his age. If the child is roughly in the top 7th percentile then the diagnosis can be made. Below that the symptoms may give a good bit of trouble but not eough to make criteria for the diagnosis. There is a handy diagnosis available for this situation and may fit your child. From the DSM (diagnostic manual):
Attention-Deficit/Hyperactivity Disorder NOS 314.9
"This category is for disorders with prominent symptoms of inattention or hyperactivity-compulsivity that do not meet criteria for Attention-Deficit/Hyperactivity Disorder."
So is is not a case of "have it" as it is not really a disease but a disorder. Mostly it is due to the genetic makeup of the child but can occur with some other pre and post natal causes. For the most part, there is nothing broken or nothing wrong with these kids. This is usually seen as a developmental disorder. Yours sounds like a case of heredity as your older son is adhd.
The best thing you can do is to become educated on the disorder. Here are some sites that follow the scientific research. Russel Barkley is currently considered the top person in the field. Chadd a support site of ADHD. Very good.
Basically, if you know what the disorder is and have a good grip on the dynamics then the management is pretty much a logical extension.
Vickie gives very good advice. Behavior management is specifically very productive in working with adhd kids. There are a number of methods available. Might be worth checking out.
Good luck. Raising an adhd kid is many things but never dull.
Dizfriz
Good luck
MetisRebel
Sounds interesting, do you have an accessible cite on this?
What we do know that if you take away the behavior modification methods used for adhd kids the go back to ground zero. There is apparently little carry over. One they are reestablished then they become effective again. A good metaphor is diabetes. You can control the disease with medication, diet, and exercise. "OK, it is fixed" Quit doing these and you are back to where you were when you started. Like diabetes adhd is a chronic condition and the treatment must be maintained for it to be effective.
Cleo (my grandmother's name...like it)
There are are a number of things you and do to help but I am going to focus on one. I call it acknowledgments. It is not praise, it is simply acknowledging good decisions. "You did that the first time I told you.", "You started to get mad but you controlled it--good job". Think of these as attaboys, done goods, verbal and visual thumbs up. They do not have to be a big deal, in fact I would suggest making them a matter of fact response to good decisions. These kids really do not have a good feel for what good decisions are. Our job is to let them know and the best time is when they make these good decisions point of performance. You can tell a kid what to do and it has little impact. Show him and it can change behaviors a lot. Do this ..50 to 100 times a day,like coins falling from a slot machine, you will be surprised at the effect. Another benefit is that you are laying a base of approval and conveying to the kid the idea that "he" is ok. His decisions are another matter. These kids are always in trouble and don't know why. As one person said to me "People were always mad at me I did not have a clue as why." Show them you approve of "them" but not their behavior decisions. This lack of connect between behavior and consequence is an effect of the disorder. It is a prime area to work.
To say raising adhd kids is a challenge is a huge understatement. It is worth it when they are grown and are happy, healthy, productive adults...usually still adhd but doing well.
Dizfriz