R.J.
It's highly unlikely that your son has ADHD...in large part...because it's ALMOST IMPOSSIBLE to diagnose that early, and most people DON'T have it. (I do, and my son probably does, but at 7yo it's really too early to tell for sure.)
The way people diagnose "disorders" is by what's different. For a child that young, that would mean that instead of the hyperactivity/distractability (which is dead normal for that age group)...they'd be looking for OTHER symptoms of ADHD. Most commonly, ungodly attention.
Yep.
Along with ADHD and the oh-so-well-known dispersed focus...ALWAYS comes hyper-focus. With an adult we're talking 12-36 hour stints -with no sleep and minimal eating even minimal bathroom breaks- if left to their own devices. With young children, we're talking HOURS of intense, focused, concentration on something that they're interested in. (Hyperactivity is actually ALWAYS present as well...but it can be mental hyperactivity or physical hyperactivity or a combo of both...mental hyperactivity is commonly misunderstood by most people as daydreaming or spacing out).
But while hyper-focus always comes along with adhd, just like hyperactivity isn't limited to ADHD ... there are other disorders as well as other PERSONALITIES that exhibit hyper-focus.
Anyhow, ADHD is a description of how some of our brains work. Just like Dyslexia, Dysgraphia, Autism, Genius, Giftedness, Bipolarity is a description of how those people's brains work. It's very very difficult to diagnose ADHD in young children (or Bipolarity, or Dyslexia)... for the simple reason that while the brain would still be functioning the way that an ADHD brain functions, most of their peer group is ACTING the same way, just for different reasons. Just as it's durn near impossible to diagnose dyslexia before a child is reading, it's really really hard to accurately disgnose ADHD without several years of patterned behavior, a more mature brain, and having ruled out the "usual suspects" (diet, sleep, allergies, other disorders such as giftedness...although many if not most ADHD kids are in the gifted range). The negatives of ADHD are brought to the forefront by our schooling system (couldn't DESIGN a system worse for most adhd kids)...and usually a few years in, when it becomes apparent that all the other kids are able to x,y,z, that your child can't. HOWEVER, the adhd kid is capable of about 15 things that most other children aren't. But those things aren't usually prized until adulthood.
So while it's unlikely your son has ADHD, it IS possible, especially if you or dad is ADHD...and it's of course desireable to diagnose as early as possible so you can teach to their strengths...it's very very hard to this young. NEVER depend on a pediatrician or school teacher for a diagnosis...ALWAYS go with a psychologist specializing in ADHD...and expect about a 3 hour testing process, that may come back as "possible" rather than "yes" or "no".
So take a deep breath and relax, you've got a lot of room & time in front of you. :) In the meantime, though feel free to read up. "You mean I'm not Lazy, Stupid, or Crazy???" by Kate Kelly and Peggy Ramundo is a good place to start...as are the YahooGroups that are ADHD specific.