Klay Alexander Thompson was born on February 8, 1990, in Los Angeles, California, to Julie and Mychal Thompson. He comes from a biracial family with strong athletic roots. His father, Mychal Thompson, was the first overall pick in the 1978 NBA Draft and played for the NBA's Portland Trail Blazers and Los Angeles Lakers. Klay has two brothers, Mychel and Trayce Thompson. Mychel briefly played in the NBA, while Trayce is a professional baseball player.

Childhood and Education

During his early childhood, Thompson's family moved to Lake Oswego, Oregon, where he attended local schools and formed a close friendship with future NBA star Kevin Love. Later, the family relocated to Ladera Ranch in California. There, Klay enrolled at Santa Margarita Catholic High School, where he began to make a name for himself in basketball.

At Santa Margarita, Thompson's basketball performance quickly gained attention. He set a school record by hitting seven three-pointers in a single game during a state championship contest. For his efforts, he received several accolades, including Division III State Player of the Year, League MVP, a spot on the First-Team Best in the West, and recognition as an EA Sports Second-Team All-American.

College Career at Washington State University

Following high school, Thompson attended Washington State University, where he solidified his reputation as a talented shooting guard. In his freshman year, he averaged 12.5 points per game and quickly became a key player on the team. Over his college career, he continued to improve and was named the Most Outstanding Player of the Great Alaska Shootout. Additionally, he became the third-fastest player in WSU history to score 1,000 points. He also made history by becoming the first Cougar to be named Pac-10 Player of the Week three times in a single season and was a nominee for the John R. Wooden Award.