I found information on your son's "small hole" on emedicine.Com. It is called a "preauricular pit". I have one as well, it has never really caused me any problems. Most doctor's say that if it is not causing any problems, i.E. Infection, swelling, redness, etc. To simply leave it alone. I found that if there are problems with having the ear pit, there are medical procedures to correct them.
This characteristic is mostly associated with other syndromes, such as bor, which I had never heard of until found the information on emedicine. Com.
I have two friends that have them as well and we were curious about them which is why I searched the internet. Good luck in your search for more information.

Mom mom has one, my older sister has one, and I was born with two, one on each ear. I just found out the medical term of it by this post. My sister got hers infected and they drained it, but she still has that smell. I actually got my left pit infected real bad when I was 9 years old by picking the skin on and around it (this was about 20 years ago). I had to get an operation and they actually cut out the whole upper flap part of my ear, got like 30 or so stitches. So now I have just one pit and I am very careful to make sure I don't mess with the other ear pit. Hope this info helps.