I tried looking for this tale, and do not know where to begin - I remember it started with a King (who had 13 sons - busy man) who saw a Swan with 13 Cygnets
and noticed it kept chasing one away.
He was told because 13 children were unnatural, and he sends his oldest son away. That's all I remember
He was told because 13 children were unnatural, and he sends his oldest son away. That's all I remember

