You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Greece

Context:
The principal gods of the ancient Greek religion were the Dodekatheon, or the Twelve Gods, who lived on the top of Mount Olympus. The most important of all ancient Greek gods was Zeus, the king of the gods, who was married to Hera, who was also Zeus's sister. The other Greek gods that made up the Twelve Olympians were Demeter, Ares, Poseidon, Athena, Dionysus, Apollo, Artemis, Aphrodite, Hephaestus and Hermes. Apart from these twelve gods, Greeks also had a variety of other mystical beliefs, such as nymphs and other magical creatures.

Question:
Who was Zeus's sister?

Hera