J. (and others)
Yes, bedwetting is genetic. My husband, father and two boys have had issues with it. We've tried limiting beverages in the evenings, cutting out milk, alarm clocks (that only woke me up) and waking them up ourselves twice a night. Nothing worked.
I called my pediatrician and he recommended a device called the Potty Pager. It is a small device that is hooked to their underwear at night. It vibrates when they wet. I don't quite understand how it trains them but it worked. It is not an instant fix. It took my boys a few of weeks to "be trained" but they did it on their own with out medications, nasal sprays, and I'm getting a good night's sleep for the first time in a year.
The website is http://www.pottypager.com/. The phone number is 1-800-497-6573. Call and talk to them. The cost is about $70 per pager and you can supply your own batteries if you chose. The batteries last through about three to four bed wettings.
Just be sure to love your son when he has an accident. My husband and I give high praise when they are dry and the boys know it is their responsibility to get up and change their sheets if they are wet. The sheets are then to appear in the laundry room and I wash them wihtout question. This builds the accountability.
I wish you the best of luck. I've been there. My boys are 8 and 10 and are happily dry 99% of the time.