Genetics are fascinating. I always tell my kids that genetics are like rolling the dice--you're never sure what you're going to get.
I am Jewish, Irish, and German (and some African-American rumored to be about five generations back) on my mother's side; Welsh and English on my father's side. My mother, grandmother, great-grandmother, and so on look Jewish more than anything (although my grandmother also had some African-American features). My dad's side is very blonde, blue-eyed, and fair. I am a mixture of both parents: light green eyes, dark hair, and light-medium coloring. The kids' dad is Hispanic (dark hair, dark brown eyes, medium-dark complexion), but both kids are blonde haired and light eyes--my daughter has grey-blue eyes and my son has light greenish-brown. My daughter tans very easily, so much so that in the summer she looks like a surfer girl, but my son is so fair that we have to lather sunscreen on him or he will burn.
I was very surprised, as was their dad, that they came out so fair. Who knew? Especially considering that dark complexion is more prevalent on both sides.