All of DS's younger siblings don't wet the bed either (well, except for the baby. ;)) I didn't figure it out for years.. until his constipation got so bad he got something called encopresis (soiling) last Spring. It's actually caused by constipation and basically there was a blockage in his intestines. I then started paying more attention and realized it was a big part of the problem. He too would take for-ev-er in the bathroom--10 minutes was the norm and it's not like he was engrossed in a story or something. ;) This was normal for him--so we just didn't realize it. (Kind of how kids with vision problems don't think there is anything wrong because not seeing is normal for them.)
You could talk to your GP about it--or try OTC Miralax or something similar. We also use these gummy fiber supplements which have 5 grams of fiber in them and encourage him to drink a lot of water (which was the opposite of what we were doing because of the bed wetting) and be active.
I am intrigued Umsami (sorry if this is a hijack).
DS is 7yo & still wet at night. He is good about wearing a night-diaper, though, but may not be forever. Even his 3yo little brother is dry at night.
Your constipated son -- did he used to take ages to go to the loo, or did he just not go? How did you realise constipation was a problem?
DS is the only one in the family who takes like 10 minutes for a poo, (the rest of us are quite quick about it) which I thought was just normal for him, but now I wonder...