Go consult the Oracle of what will happen if I have a son in law.
Yes King Acrisius.
Bad News and the Consequence
Your daughter will bear a son, who will one day kill you.
It is sufficient to forbid her from all male company for all her days.
King Acrisius is knows that his daughter Danae is ready for a husband, but he may not be ready for a son in law. He goes and sends a messenger to the Oracle of Delphi for future news.
The messenger is at the Oracle and she results with “you will bear a son, who will one day kill you”.
The king beheads the messenger for bad news, the king realizing he needs to keep his daughter away from all male company, locking her up in a tower with only a slit through the window. Then the king sees that she has had a baby, Danae naming him Perseus.