I have blue eyes, and my boyfriend has green eyes (though they look orange sometimes). What color eyes will our kids have?
Blue, green or hazel most likely. Brown maybe, if you adopt.
Whats the colour of your neighbor?
LONG ANSWER
This is a lot more complicated than it seems, because eye color is controlled by at least three pairs of genes, and possibly four. Only two of these are understood.
One of the pairs is called ECL1, and determines blue/green eyes. The other is ECL3, and determines blue/brown eyes.
First, you look at the ECL3 genes. If a person has two brown eyed genes (BB), he will have brown eyes. If a person has one brown and one blue (Bb), he will have brown eyes. If a person has two blue genes (bb), then he will not have brown eyes, and you look at the ECL1 genes to find out if he will have green or blue eyes.
The ECL1 genes determine whether a person will have blue or green eyes. If a person has two blue genes (bb), he will have blue eyes. With one green and one blue (Gb) or with two green (GG), the result is green eyes.
Now to apply this to your situation. Your ECL3 genes are easy to determine. Your blue eyes and his green eyes will give you both the same (bb) configuration. You children cannot have brown eyes.
The ECL1 genes are a bit more tricky. You have two blue eyed genes (bb) and he has either two green (GG) or a blue and a green (Gb). If your boyfreind has two green genes (GG), your children will have green eyes. If he has a blue and a green (Gb), your children have a 50-50 chance of having either blue or green eyes.
SHORT ANSWER
Your children will have either blue or green eyes. It depends upon what color eyes your boyfreind’s parents have, because that determines what genes he has. If one of his parents has blue eyes, then your children have a 50-50 chance of being blue or green eyed. If both are green eyed, your children will have green eyes. Other combinations make it more complicated. If you could tell what color eyes his parents (or even better, parents and grandparents) have, I could give you some pretty exact percentages.
Wow, what a complete answer, thank you Number Six 
I don’t remember what color his parents eyes are, but his little brother has blue eyes. I guess that means he has a blue gene too, so we’ll probably have half green eyes and half blue eyes.
You got it. Each child has a 50-50 chance of being green-eyed or blue-eyed, so it’s possible for you to have all blue-eyed children or all green-eyed children.
Your situation was actually less complicated than most. There are six different genetic combinations for brown eyes, which makes for some really interesting results, and geneticists still haven’t figured out the genetics of hazel or gray eyes.
With my fiancee and I, it’s easy. She’s Filipino, which makes her almost certainly Brown-Brown, which means that it matters not what color my eyes are, our children will be brown-eyed.
This is likely to be true but I don’t think it can be said with 100% certainty.
If both parents were Gb on ECL1 it is possible that the boyfriend is GG while his brother is bb. Meaning that all Ariadne’s kids would have green eyes.
Knowing the eye colors of the parents could still help nail this thing down.
The best way to tell for sure would be for Ariadne to have kids and then look at their eyes.
I have green eyes, my husband has blue eyes. One son is blue eyed, the other was green eyed.
Good catch. We can’t be absolutely certain that Ariandne’s boy freind has an ECL1 blue-eyed gene. Given that one child is blue-eyed, and the other green-eyed, the odds of his parents being Gb/bb are four times that of the chances of the parents being Gb/Gb. This means that the odds of a blue-eyed child are 4/51/2=0.4, and the oddds of a green-eyed child are (4/51/2)+1/5=0.6. So the exact odds, given the information we have are 60% green, 40% blue.
My parents are like that. One has blue the other green, and they had two green eyed kids.