4 Answers

If you are not speaking of Caucasian children you are adopting, my initial thought would be there is some major Caucasian genealogy in one or both of your DNA.  Worth checking out? 

This i believe why you had blood tests years ago, due to having slaves and the coupling with whites sometimes a throw back occurs and a white baby is born and vice versa, i imagine this has caused upsets with couples as the man think his female spouse has been cheating on him- a movie was made many years ago on this Dilemma.   My wife had a dark baby due to Spanish blood in her ancestry --- Documentary i saw insinuated there were a lot of people in the U.S. who had white/ black blood in their blood line who don't know it.  :)

Bit of an answer here my friend,,or at least it shows it is not just you,,there are quite a lot of people out there that have the same happening as you two..>>>>>>>><<<<<<<..https://www.youtube.com/watch?v=xhkYTkzjQVs

A friend of mine is black and so is his wife. They had two children and they are both very light skinned with blonde hair and blue eyes. He is still waiting for his kids to turn black. It's been over 40 years and he is still waiting. We all just laugh. 

country bumpkin

This is funny!