I find eye color fascinating, and yet many people take it for granted. In fact eye color is usually dumbed down into two categories, Dominant traits vs Recessive traits. Blue eyes are a recessive trait along with other unusual colors such as green, amber, hazel, grey, etc. You can also be a carrier for other colors which is based on your genetic makeup.
Let us try and example to clarify, say Dad has brown eyes, but he’s a carrier for blue, green, hazel. Mom has brown eyes as well, and a carrier for blue, and amber.
Brown is a dominant trait and all other colors are recessive. Odds are their children will most likely have brown eyes as well, but since they’re both carriers of the recessive blue, there’s a chance that their children could have blue eyes.
When both parents have blue eyes, and you have green eyes. Technically blue and green are both recessive traits, so your parents are both carriers of the green eye color and it just happened to come out in you.
For comparison, my dad has blue eyes, mother brown. I have blue/grey eyes, my sister has blue and my brother has hazel. Because my dad has a recessive eye color, he doesn’t have the brown (dominant) trait, and a carrier of at least green, grey and hazel And my mother was a carrier of blue, grey and hazel as well.
Keep in mind that eye color, hair color, etc. are a bit more complicated than just dominant vs. recessive but this is how basic biology explains it.
Here in the US, where 1 in 6 people have blue eyes, having green eyes becomes rare.
They (Green eyes) are most common in Northern and Central Europe. They can also be found in Southern Europe and North Africa. In fact, Turkey, at 20%, is the country with the largest percentage of green eyes. In Iceland, 89% of women and 87% of men have either blue or green eye color. A study of Icelandic and Dutch adults found green eyes to be much more prevalent in women than in men. Among European Americans, green eyes are most common among those of recent Celtic and Germanic ancestry, about 16%.
Source
So countries that have a higher percentage of fair eye color also have more people with green eyes. I might be rare here, but in Scotland for example, I could
blend in.
My boyfriend has a red beard, I’ll tease him about being Red Beard the Pirate, which compliments my redhead quite well.
Other than that he has dark hair. Which he thinks of as odd, but actually it is quite common. There are different genes for red hair on your head versus red hair in your beard (if you’re a guy, girls get it lasered), and the genes for red beards are much more common than red heads.
Look closely at guys’ beards; you’ll often find they’re sort of calico, a mix of black and brown and red and white and grey.
This kind of mix is very common. 
I have red (don’t believe everything you read) that the Udmurt People are the most red haired in the world, even more than the Irish.
I don’t know of any data to back that up, but they do have a lot of redheads.
~XO