Ancient Egyptian culture was rife with intermarriage between royal siblings. Cleopatra continued that tradition.
It appears that Cleopatra married two of her brothers. First, she married her oldest brother Ptolemy XIII. Following his death, she married her younger brother Ptolemy XIV and ordered him poisoned.

Cleopatra had a troubled relationship with her siblings, whom she married, killed, and went to war against.
Who Was Cleopatra?
After Alexander the Great’s death, Egypt became a Hellenistic kingdom under the rule of Alexander’s general Ptolemy. Thus, she was a queen from a Macedonian line. Her family combined traditional Egyptian cultural elements with Hellenistic traditions.
Cleopatra was a unique figure in her family. While her predecessors on the throne had refused to learn the local language, she was fluent in the local traditional tongue.
When her father Ptolemy XII died, the crown was passed on to Cleopatra and her brother Ptolemy XIII. The evidence strongly suggests that the two siblings were married, although there is no conclusive proof.
Her family had already broken the Greek taboo against marrying siblings when Ptolemy II had married his sister. Therefore, Cleopatra’s marriage to her brother was utterly normal in Ptolemaic Egypt.
However, Cleopatra was no shrinking violet queen. She seems to have made an effort to minimize her brothers’ power. Therefore, Ptolemy XIII organized a conspiracy against his sister. The two siblings tore Egypt apart with a bitter civil war.
Cleopatra Fights Her Siblings
Ptolemy XIII and his allies forced Cleopatra to flee to Syria. While the famous queen raised an army in exile, her sister Arsinoe VI also claimed to be Egypt’s rightful ruler.
The siblings battled over Julius Caesar’s affections, as he was becoming the most powerful man in the dying Roman Republic. Caesar’s rival Pompey the Great sought asylum in Egypt, and Ptolemy XIII pretended to grant it before cutting off Pompey’s head and presenting it to Julius Caesar.
The move deeply angered the mighty general. Caesar then sided with Cleopatra against her brother/husband. Also, he began a legendary affair with her as Caesar helped her return to the throne, the scorned brother allied with Arsinoe against their clever sister.
Cleopatra and her Roman allies beat her disappointed siblings in the Battle of the Nile in 47 BC. Ptolemy XIII reportedly drowned in the river after the battle. One version claims he was fleeing, while the other that he was falsely lured into negotiations and assassinated.
Cleopatra Marries Another Brother
The happily widowed Cleopatra was now appointed co-regent with her 12-year-old brother Ptolemy XIV. However, the married queen was at that time cohabitating with Caesar. Their union produced a son, the unfortunate Caesarion.
The Roman general soon left Egypt to regain his position in Rome and was famously assassinated by a group of Senators in the Forum.
Cleopatra had traveled with him and remained there following her lover’s death. She took the opportunity to have her brother poisoned to clear the path for her son’s rule.
Cleopatra Finds A New Roman General
Following Julius Caesar’s death, the triumvirate of Octavian, Marcus Lepidus, and Marc Antony ruled over Rome in an uneasy alliance. Cleopatra entered a relationship with Marc Antony and allied with him militarily and politically. Among her lover’s many actions to help Cleopatra, he killed her sister and rival Arsinoe IV while in exile at Ephesus.
She had two children with Antony, both of whom the Roman general recognized. However, Antony kept busy and married a Roman noblewoman with whom he had two further children.
However, Antony returned to meet Cleopatra, and they renewed their partnership fully. As relations between Octavian and Antony soured, Cleopatra found herself involved in the tumultuous Liberators Civil War.
Octavian was a very clever rival, and he exploited the entanglements between Antony and Cleopatra for his ends. The young claimant to the throne accused Antony of selling our Rome in favor of a foreign queen’s interests.
The forces of Octavian finally met with those of the beleaguered lovers in the Battle of Actium. Rather than be taken prisoner by Octavian and paraded in Rome, Cleopatra committed suicide in 30 BC. She tried to leave her son Caesarion in charge, but Octavian had him killed soon after.
Cleopatra remains a legendary figure today, with countless movies and books on her appearing. While they often emphasize her romantic relationships with influential Roman leaders, they do not usually engage with her somewhat messy family life.