What does it mean when the sclera part of your eye is blue?

Ok so ever since ive been born the sclera part of eye has always been a slight blue. It really accents my eyes but it isnt a dark blue to where there is a problem. My mother has it and so does one of my sisters so im guessing its hereditary but some people tell me that is considered a phoa..or i have a disease. When i go to a doctor they never seem to mention it so im curious as to know what exactly it means.