As times modernize, several monarchies have made succession gender-neutral, including the UK’s royal family.
Historically, the firstborn would not inherit the throne if the child was a girl. But a 2011 decision made by leaders of the 16 Commonwealths under British rule changed all that. Now, the royal couple’s firstborn, regardless of gender, has a right to the crown. So Kate’s baby will be third in line to the British throne at birth.