Ashley Madison proves that. LOL
Su Wong marries Lee Wong. The next year, the Wong's have a new baby. The nurse brings to them a lovely, healthy, bouncy, but definitely Caucasian, white baby boy!
"Congratulations," says the nurse to the new parents. "What will you name the baby?"
The puzzled father looks at his new baby boy and says, "Well, two Wongs don't make a white, so I think we will name him Sum Ting Wong."
Was the implication that 30% of kids are fathered by someone other than the assumed father?
Skewed data source.
My bet is that only men with reasons to be suspicious have the child tested.