Bruce Jenner may now be Caitlyn Jenner, but his sex change doesn’t change the fact that Caitlyn could “whip your ass,” the eldest son said on Instagram.

Burt, Jenner’s 37-year-old son, took to Instagram to defend his dad, noting in an Instagram post that while a “lot has changed” — posting a picture of Caitlyn — “the most important stuff didn’t,” according to a Page Six report.

He added that his dad “still loves toys, fun toys, still likes to go fast, still loves adrenaline” — and, he added interestingly, Caitlyn Jenner will “still whip your ass at … ANYTHING.”

Calling his dad’s critic’s “haters,” Burt Jenner said his dad could “whip your ass at 65 with implants.”

He posted another picture of Caitlyn Jenner with her fist int he air, behind two young girls who are sitting in a pink toy car for a humorous effect.

Caitlyn Jenner won a legal victory on Friday as a judge approved a request to change her name and gender officially.

Caitlyn Jenner’s transition from a man to a woman has taken the world by storm and brought attention to transgender issues in recent months with his decision to make the switch. Formerly known as Bruce, Caitlyn Jenner is a retired American athlete best known for winning the men’s decathlon in the 1976 Summer Olympics.

In later years, he became famous for appearing on E!’s hit reality TV program Keeping up with the Kardashians. After transitioning to Caitlyn Jenner, she is now starring in the show “I Am Cait,” which focuses on her gender transition.

Jenner made his big reveal of her gender identification as a trans woman back in April, when she did an interview with Diane Sawyer on 20/20.

The announcement provoked a firestorm of debate around the country, and the world, about transgender issues.

Jenner is now 65, and she has had an eventful life so far. She was born on Oct. 28 in 1949 in Mount Kisco, New York. Her younger brother, Burt, died in a car accident shortly after Jenner won gold at the Olympics in 1976.

Jenner has struggled with dyslexia since she was a young child. She was a gifted athlete, and earned a football scholarship at Graceland College in Iowa. However, she suffered a knee injury that forced her to switch to decathlon. Her track coach recognized her potential, and encouraged her to pursue decathlon. Her debut in at the Drake Relays in Des Moines in 1970 resulted in a fifth place finish. She graduated in 1973 with a physical education degree.

Jenner first tried to enter the men’s decathlon in the 1972 U.S. Olympic trials in Oregon, and was able to make the Olympic team. She finished 10th in the decathlon int he 1972 Summer Olympics in Munich.

She spent the next four years vigorously training by day while selling insurance at night. Jenner won the American championship in decathlon in 1974, prompting her to be featured on the cover of Track & Field News’ August 1974 issue. She also won the French national championship the next year. Finally, at the Olympic Games in Montreal, she won the gold medal, beating the world record with a score of 8,616 points. She had an iconic moment when she took an American flag from a spectator and carried it during the victory lap, spurring a tradition that exists to this day.

Jenner became so famous after the Olympics that she was featured on the Wheaties breakfast cereal box in 1977.