Curious about yellow eyes

I work for the Boys & Girls Club. Last week I noticed that a 12 year old black male, had yellow eyes where they should be white. I don't know a lot about these things, but I have always heard that was a sign that something was wrong with the liver. I questioned him about how long they had been that way. He said for quite a while. He has not seen a Dr. lately. I checked his twin brother and his eyes were white. He said he didn't know why his brothers eyes were yellow, but his mom's were a little also.
I hate to jump to a panic or anything, but is this enough information to become concerned? I would hate to talk to his parents about something like this and be completly  ignorant about it. Thanks for any help you can give me. He's a good kid.