The colourpoint gene is a form of albinoism, according to my vet. That's one way a cat can get blue eyes. It's probably the most problem-free way to get blue eyes, from a health standpoint.
Another form is found in blue-eyed white cats, who are very often deaf. The lack of melatonin seems to affect hearing. (Same as in Dalmation dogs who don't have all-black ears.)
A much rarer source of blue eyes is the Oyos Azule gene, a very rare trait which showed up relatively recently in New Mexico. Unfortunately, kittens carrying two copies of the gene seemed to have had some problems, so plans to develop a breed have stalled.
As to whether Siamese are more intelligent, I'm not so sure. They are talkative and want to be with their people, so some people view that as being more intelligent.
Personally, I've had two super-smart cats in my life who were both long-haired tabby moggies with some Persian heritage. My present cat is a Siamese. He's smart enough, but he doesn't seem more intelligent than them.
Last edited by Nuliajuk; 06-17-2015 at 09:15 PM.