Princess of Monaco gives birth to royal twins -- but who will be heir?

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Princess of Monaco Gives Birth To Royal Twins - But Who Will Be Heir?

Prince Albert the second and Princess Charlene of Monaco welcomed a set of royal twins -- but only one will be the future heir to the throne.

Forty-two cannons were fired in honor of the twins, who were born via a cesarean section at the Princess Grace Hospital, name for Albert's mother, Grace Kelly.

The twins are the first children for Princess Charlene, a 36-year-old former South African Olympic swimmer. Prince Albert, 56, has two older children who are considered illegitimate by the House of Grimaldi.

The princess gave birth to Gabriella at 5:04 and Jacques at 5:06. Though he was born second, Jacques is the crown prince thanks to the Mediterranean's male inheritance laws.

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Princess of Monaco gives birth to royal twins -- but who will be heir?
MONACO, MONACO - DECEMBER 10: In this handout image provided by Monaco Centre de Presse, Canon's fire at the Palace of Monaco as Princess Charlene Of Monaco And Prince Albert II Of Monaco welcome twins on December 10, 2014 in Monaco, Monaco. (Photo by Charly Gallo/Monaco Centre de Presse via Getty Images)
In this Nov. 19, 2014 file photo, Prince Albert II of Monaco kisses his wife Princess Charlene on the balcony of the Monaco palace during the Monaco's national day ceremony. Monaco is expecting a double dose of royal babies _ but only one twin will get to be the principality’s future ruler. (AP Photo/Lionel Cironneau, File)
MONACO, MONACO - DECEMBER 10: In this handout image provided by Monaco Centre de Presse, Canon's fire at the Palace of Monaco as Princess Charlene Of Monaco And Prince Albert II Of Monaco welcome twins on December 10, 2014 in Monaco, Monaco. (Photo by Charly Gallo/Monaco Centre de Presse via Getty Images)
SAS Prince Albert II of Monaco and his wife Princess Charlene inaugurate the Yacht Club de Monaco’s new building, Friday, June 20, 2014, in Monaco. Founded in 1953, the Yacht Club de Monaco brings together more than 1200 members from 60 nationalities.(AP Photo/Lionel Cironneau)
Monaco's guard fires a cannon to celebrate the birth of Prince Albert and Princess Charlene of Monaco's twins, in Monaco, Wednesday, Dec. 10, 2014. Princess Charlene has given birth to twins Jacques and Gabriella. (AP Photo/Lionel Cironneau)
Royal twins of Denmark (AP Photo/Polfoto,Joachim Adrian, Pool (Prince Frederik of Denmark))
In this Jan. 14, 2011 file photo, Denmark's future monarch's Crown Prince Frederik and Crown Princess Mary present their newborn twins during their first public appearance in Copenhagen, Denmark. A double dose of royal baby noise should soon be resounding in the hilltop palace of Monaco as Her Serene Highness Princess Charlene gives birth to twins _ one of them destiny's child, first in line to reign over the Mediterranean principality. (AP Photo/Polfoto/Finn Frandsen, File) DENMARK OUT
Prince Albert II of Monaco with his wife Princess Charlene, arrive at the "Monaco Red Cross Ball", Friday, Aug. 1, 2014, in Monaco. The Monaco Red Cross Ball is a charity gala evening brings together high society as well as donors from all over the world. (AP Photo/Lionel Cironneau)
Prince Albert II of Monaco with his wife Princess Charlene wave from the Monaco palace to the Monaco's national day ceremony, Wednesday Nov. 19, 2014. Monaco's Fete Nationale has been celebrated since the reign of Prince Charles III in 1857. Originally falling on the saint's day of the reigning prince, Prince Albert II decided to keep the date his father celebrated, Saint Rainier's Day, 19th November.(AP Photo/Lionel Cironneau)
BERLIN, GERMANY - FEBRUARY 06: Prince Georg Friedrich Ferdinand Prussia and Princess Sophie of Prussia pose inside the AUDI Lounge at the Marlene Dietrich Platz during day 1 of the Berlinale International Film Festival on February 6, 2014 in Berlin, Germany. (Photo by Gisela Schober/Getty Images for Audi)
French duke of Anjou, Louis Alphonse de Bourbon (L) and his wife Maria Margarita Vargas Santaella attend a mass marking the anniversary of the foundation the Hotel des Invalides by Louis XIV on September 19, 2010 at the Invalides in Paris. AFP PHOTO / MARTIN BUREAU (Photo credit should read MARTIN BUREAU/AFP/Getty Images)
FRANCE - JUNE 03: Princess Marie Marguerite Duchess of Anjou, Prince Louis of Bourbon, Duke of Anjou and SAR Princess Eugenie of Bourbon in Paris, France on June 03, 2007. (Photo by Frederic SOULOY/Gamma-Rapho via Getty Images)
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Albert reportedly didn't know the sex of the children before birth. "It is one of the beautiful surprises that life offers us," he said.

Still, Monaco's succession laws give priority to boys. The only woman ever to reign was Princess Louise-Hippolyte in 1731. If both twins had been girls, the baby born first would have taken the throne.

In 2002, Monaco's parliament changed its constitution so that royal power could pass from a reigning prince with no descendants to his siblings-possibly Albert's two sisters, if he did not have legitimate heirs.

The royal household dates back to the 13th century, but Jacques and Gabriella are its first twins-but they're hardly the first royal twins in Europe.

King James I of Scotland and his wife Joan Beaufort had the United Kingdom's lone pair in 1430, and many more across the pond have followed. In 2013, the Prince of Prussia Georg Fredrich and his wife Princess Sophie of Isenberg had twin boys. In 2011, Crown Prince Frederik of Denmark and his wife Mary had twins, and the year before, the Duke of Anjou, Prince Louis Alphonse, and his wife Maria Margarita Vargas Santaella had their own.

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