In an interview with ET last month, George's dad, Nick Clooney, gushed about his grandchildren, and revealed how his son has changed since becoming a father.
See more photos of the couple together:
George Clooney and Amal Clooney together
George Clooney and Amal Clooney together
PARIS, FRANCE - FEBRUARY 24: George Clooney and Amal Clooney arrive at the Cesar Film Awards 2017 at Salle Pleyel on February 24, 2017 in Paris, France. (Photo by Franï¿½is Pauletto/Corbis via Getty Images)
(FILES) File photo dated February 24, 2017 shows US actor George Clooney and his wife British-Lebanese lawyer Amal Clooney as they arrive for the 42nd edition of the Cesar Ceremony at the Salle Pleyel in Paris.
The couple welcomed their twin babies, Ella and Alexander, June 6, 2017 in London, the actor's publicist said. The 39-year-old human rights lawyer and 56-year-old Hollywood star -- both first-time parents -- tied the knot in Venice in 2014.
/ AFP PHOTO / bertrand GUAY (Photo credit should read BERTRAND GUAY/AFP/Getty Images)
PARIS, FRANCE - FEBRUARY 24: George Clooney and Amal Clooney arrive at the Cesar Film Awards Ceremony at Salle Pleyel on February 24, 2017 in Paris, France. (Photo by Rindoff/Charriau/Getty Images)
LONDON, ENGLAND - JANUARY 09: George and Amal Clooney attend the Netflix special screening and reception of The White Helmets hosted by The Clooney Foundation For Justice with George and Amal Clooney, at the Bvlgari Hotel on January 9, 2017 in London, England. (Photo by David M. Benett/Dave Benett/Getty Images for Netflix )
NEW YORK, NY - SEPTEMBER 20: (AFP OUT) Actor George Clooney (L) and wife Amal Clooney attend a Leaders Summit for Refugees during the United Nations 71st session of the General Debate at the United Nations General Assembly on September 20, 2016 in New York, New York. (Photo by Peter Foley - Pool/Getty Images)
CANNES, FRANCE - MAY 12: George Clooney and Amal Clooney attend the 'Money Monster' Premiere during the 69th annual Cannes Film Festival on May 12, 2016 in Cannes, France. (Photo by Tony Barson/FilmMagic)
VATICAN CITY, VATICAN - MAY 29: George Clooney and Amal Clooney attend 'Un Muro o Un Ponte' Seminary held by Pope Francis at the Paul VI Hall on May 29, 2016 in Vatican City, Vatican. (Photo by Franco Origlia/Getty Images)
(FILES) File photo dated February 11, 2016 shows US actor George Clooney (R)and his wife Amal arrive at the 66th Berlinale Film Festival in Berlin.
George and Amal Clooney welcomed their twin babies, Ella and Alexander, on June 6, 2017 in London, the actor's publicist Stan Rosenfeld said. The 39-year-old human rights lawyer and 56-year-old Hollywood star -- both first-time parents -- tied the knot in Venice in 2014. / AFP PHOTO / John MACDOUGALL (Photo credit should read JOHN MACDOUGALL/AFP/Getty Images)
WESTWOOD, CA - FEBRUARY 01: Amal Clooney and George Clooney arrive at the premiere of Universal Pictures' 'Hail, Caesar!' at Regency Village Theatre on February 1, 2016 in Westwood, California. (Photo by Gregg DeGuire/WireImage)
WESTWOOD, CA - FEBRUARY 01: George Clooney and Amal Clooney arrives at the Premiere Of Universal Pictures' 'Hail, Caesar!' at Regency Village Theatre on February 1, 2016 in Westwood, California. (Photo by Steve Granitz/WireImage)
Lawyer Amal Alamuddin Clooney and Actor George Clooney arrive at the premiere of 'Our Brand In Crisis' held at the TCL Chinese Theater in Hollywood. (Photo by Frank Trapper/Corbis via Getty Images)
HOLLYWOOD, CA - OCTOBER 26: Amal Clooney and George Clooney attend the premiere of 'Our Brand Is Crisis' at TCL Chinese Theatre on October 26, 2015 in Hollywood, California. (Photo by Jason LaVeris/FilmMagic)
NEW YORK, NY - SEPTEMBER 29: George Clooney (L) and Amal Clooney are seen in Midtown on September 29, 2015 in New York City. (Photo by Michael Stewart/GC Images)
IBIZA, SPAIN - AUGUST 23: (L-R) Michael Meldman, Monica Gambee, Amal Alamuddin, George Clooney, Rande Gerber and Cindy Crawford host the official launch of Casamigos Tequila in Ibiza, at Ushuaia Ibiza Beach hotel on August 23, 2015 in Ibiza, Spain. (Photo by Europa Press/Europa Press via Getty Images)
IBIZA, SPAIN - AUGUST 23: Amal Clooney (L) and Founder of Casamigos Tequila George Clooney attend as Casamigos founders Rande Gerber, George Clooney and Mike Meldman host the official launch of Casamigos Tequila in Ibiza and Spain at Ushuaia Ibiza Beach Hotel on August 23, 2015 in Ibiza, Spain. (Photo by David M. Benett/Dave Benett/Getty Images for Casamigos Tequila)
US movie star George Clooney (R), accompanied by his wife Amal (L), arrives at Haneda airport in Tokyo on May 24, 2015. Clooney is now here for the Japanese premiere of his new film 'Tomorrowland', a retro-futuristic spectacle mixing environmental themes with sci-fi wizardry. AFP PHOTO / Yoshikazu TSUNO (Photo credit should read YOSHIKAZU TSUNO/AFP/Getty Images)
TOKYO, JAPAN - MAY 25: Lawyer Amal Clooney (R) and actor George Clooney (L) attends the Tokyo premiere of 'Tomorrowland' at Roppongi Hills on May 25, 2015 in Tokyo, Japan. (Photo by Atsushi Tomura/Getty Images)
ANAHEIM, CA - MAY 09: (L-R) Mia Alamuddin, actor George Clooney and lawyer Amal Clooney attend the premiere of Disney's 'Tomorrowland' at AMC Downtown Disney 12 Theater on May 9, 2015 in Anaheim, California. (Photo by Alberto E. Rodriguez/Getty Images for Disney)
NEW YORK, NY - MAY 04: Actor George Clooney and lawyer Amal Clooney attend the 'China: Through The Looking Glass' Costume Institute Benefit Gala at the Metropolitan Museum of Art on May 4, 2015 in New York City. (Photo by Axelle/Bauer-Griffin/FilmMagic)
NEW YORK, NY - MAY 02: Amal Clooney and George Clooney are seen on May 2, 2015 in New York City. (Photo by NCP/Star Max/GC Images)
NEW YORK - APRIL 28: Amal Clooney, George Clooney get dinner at Caravaggio in Upper East Side on APRIL 28, 2015 in New York, New York. (Photo by Josiah Kamau/BuzzFoto via Getty Images)
NEW YORK - MARCH 07: George Clooney and Amal Clooney get dinner at Kappo Masa sushi restaurant in Upper East Side seen out in the Big Apple in yellow on MARCH 07, 2015 in New York, New York. (Photo by Josiah Kamau/BuzzFoto via Getty Images)
BEVERLY HILLS, CA - JANUARY 11: Actor George Clooney (L) and Amal Clooney attend the 72nd Annual Golden Globe Awards at The Beverly Hilton Hotel on January 11, 2015 in Beverly Hills, California. (Photo by Jason Merritt/Getty Images)
George and Amal leave Venice town hall Ca'Farsetti after their civil marriage cerimony (Photo by Giulia Candussi/Corbis via Getty Images)
VENICE, ITALY - SEPTEMBER 29: George Clooney and Amal Alamuddin sighted on the way to their civil wedding at Canal Grande on September 29, 2014 in Venice, Italy. (Photo by Robino Salvatore/GC Images)
VENICE, ITALY - SEPTEMBER 28: George Clooney and Amal Alamuddin leave the Aman Hotel on September 28, 2014 in Venice, Italy. George Clooney is set to marry his lawyer fiancee Amal Alamuddin this weekend in Venice where they met. (Photo by PVS/GC Images)
VENICE, ITALY - SEPTEMBER 26: George Clooney and Amal Alamuddin arrive in Venice on September 26, 2014 in Venice, Italy. George Clooney is set to marry his lawyer fiancee Amal Alamuddin this weekend in Venice where they met. (Photo by PVS/GC Images)
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"Since the word came out that he was going to be a father, no question about it, he changed," Nick said. "This has nothing to do with age, but this is a different kind of maturity. When you figure out that you're going to take that standard responsibility that everybody else has done for years, and now you're on the merry-go-round. You're in the middle."
"I suspect, and I can't verify this," Nick added, "he will not get any standard rest until about December 15."
Following one of the most buzzed-about pregnancies in years, George and Amal Clooney became first-time parents when they welcomed twins -- Ella and Alexander -- on June 6, 2017.
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Hoda Kotb adopted her first child, a baby girl named Haley Joy. She was born on Valentine's Day 2017.
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Jimmy Kimmel's wife, Molly, gave birth to their second child on April 21 -- and just hours after his delivery, he was slated for open heart surgery. Kimmel opened up about the terrifying events, getting emotional on-air as he detailed his newborn's difficult journey. Thankfully, little Billy is now on track to a full recovery.
Ciara and husband Russell Wilson welcomed baby Sienna Princess on April 28 after months of public anticipation! Ciara documented the pregnancy heavily via social media up until the big day.
At 50 years old, Janet Jackson welcomed her very first child, a boy named Eissa Al Mana. She and her husband, Qatari business magnate Wissam Al Mana, split not long after.
He largely stays out of the spotlight, but reports confirmed that Jesse Eisenberg and girlfriend Anna Strout welcomed their first child in early 2017.
Benedict Cumberbatch and his wife, Sophie Hunter, grew their family by one with the birth of son Hal Auden on March 3. His big brother is Christopher, born in 2015.
Natalie Portman and her husband, choreographer Benjamin Millepied, had their second child on Feb. 22. Her name is Amalia Millipied.
Zooey Deschanel and her husband, Jacob Pechenik, had their second child in spring 2017, her rep confirmed. Little Charlie's older sister is Elsie, who was born in 2015.
Tori Spelling and Dean McDermott increased their already-full household with their fifty child, born on March 2. Little Beau is the perfect addition to "our big, beautiful and healthy family," Tori told People.
Gal Gadot gave birth to a Wonder Woman of her own in March 2017! She and her husband, Yaron Versano, were already parents to daughter Alma, born in 2011.
Backstreet Boys star AJ McLean and his wife Rochelle Deanna Karidis had the perfect name for a sure-to-be musically inclined baby: Their daughter, Lyric, was born in March.
Chad Michael Murray and Sarah Roemer excitedly announced the birth of their second child, a girl, in March 2017. Their first son was born in 2015.
"Grey's Anatomy" star Camilla Luddington and her boyfriend Matthew Alan announced the birth of their baby girl, Hayden, in spring 2017.
Pharrell Williams and Helen Lasichanh welcomed triplets (!!!) in January 2017. The little trio have an 8-year-old brother, Rocket. (By the way, this is the couple just a few months after Helen gave birth!)
Armie Hammer's wife, Elizabeth Chambers, gave birth to their second child in January 2017. The baby boy, Ford Douglas, has a big sister in 2-year-old Harper Grace.