Sexually active Popes

https://en.wikipedia.org/wiki/List_of_sexually_active_popes#Popes_alleged_to_be_sexually_active_during_pontificate

They were allowed to be married in the early Church but some like the Medicis  or Borgias had  children  but were not  married.

From the references:

George L. Williams, Papal Genealogy: The Families And Descendants Of The Popes, page 74: “Clement now made Alessandro de Medici “his illegitimate son by a slave” into the first duke of Florence” , McFarland & Company, 1998, ISBN 0-7864-2071-5

From: children of Popes

 

https://en.wikipedia.org/wiki/Category:Illegitimate_children_of_popes