Whose child are you?

Why did the King not notice sooner that this child was probably not his? As soon as this child was born and feeding, he was slaying those who had done no harm.  “Well before twelve months were gone. He’d slain nine nurse maids, one by one, Ladies highborn and free.” (ll 118-120). The child killed nine milk maids, and even raped a women and killed her husband. Why did it take all of that to think;  hmm I don’t think I am the dad. The child had to have looked very different from his father, not to mention the way he acted. How did it take fifteen years to start questioning this? If I was the King I would have started to question my wife when Gowther was at least ten years old.