Likely having the or an unusual mutation that some of us asians sometimes have that has you producing slightly less melanin, the pigment, than others. That or your body metabolizes some of it while it remains in vivo, lessening it's expression. 

It is refered to commonly as a form of albinism but that's not exactly correct. 

There is this girl in memoirs of a geisha who was pure japanese but had an extreme case if albinism in her eyes, causing them to be blue. 


Tell them this, all this, next time and they will never bother you again. Because. SCIENCE! (It's alot more but I've summarized it.) 

My farewell gift to you. The bookish, energetic Battle-chef. *deliberately misses mentioning the part about sacrisfIce*