A biological father determines the sex of his child through a sperm cell that carries either an X chromosome or a Y chromosome. If the sperm contains an X chromosome, the resulting child will be female. If it carries a Y chromosome, the child becomes male.
Roman law defined fatherhood with the phrase Mater semper certa; pater est quem nuptiae demonstrant which meant the mother was always certain while the father was identified by marriage vows. Modern DNA testing has rapidly changed family law regarding paternity to establish biological relationships.
Paid paternity leave first began in Sweden in 1976. It is now paid in more than half of European Union countries and allows a father to take time off for a newly born or adopted baby.
King Kassapa I created the Sigiriya citadel of ancient Sri Lanka between 473 and 495 CE after he killed his father king Dhatusena to claim the throne.
Darwin's frog fathers carry eggs inside their vocal pouches. Male emperor penguins incubate eggs alone while females do no incubation and each male protects his egg by balancing it on tops of his feet.