The births sent the media into a frenzy, with paparazzi lined up outside the hospital, clamouring for the first pictures, and celebrity websites outdoing one another with headlines such as "10 Reasons George Clooney Will Make a Great Dad".
Nick also confessed that there was a time when he doubted whether the Oscar victor, 56, would ever become a father. "The little boy looked like he had [George's] nose, his little profile".
"Nina swears they have George's nose", the 83-year-old shared, adding they both have dark hair.
George Clooney introduced his twin babies to their paternal grandparents in a Skype video call just two hours after their births.
The proud grandfather says he "certainly" loves the names.
The 56-year-old actor's One Fine Day daughter, Mae Whitman, took to Twitter on Tuesday to congratulate her onscreen dad on his "new additions" alongside an adorable throwback pic from the set of the 1996 film.
Nick is a big fan of Amal
"Amal Clooney gives birth to twins with attractive, average names", read one tweet.
In what seems to be one of the most highly anticipated celebrity births of the decade, perhaps just playing runner-up to the births of Prince George and Princess Charlotte, Amal Clooney gave birth to fraternal twins, named Ella and Alexander, on Tuesday morning.
"She is doing really great", George said.
"They're doing very well", he said.
"We are over the moon", Bara, who was in London with Amal and George, revealed to French publication AFP. "The babies are handsome, of course, she's attractive". He also made it clear that he knew he was older, and that many of his friends already had kids away at college, yet he still accepted the challenge with a positive attitude. According to a source, the tentative plan is to have George and Amal live and nest in their London home for the first few years of their bundle of joys' lives.