AceShowbiz - Caitlyn Jenner admitted she hasn't been a "perfect" stepfather in an honest birthday tribute to stepdaughter Khloe Kardashian. The Good American co-founder celebrated 39th birthday on Tuesday, June 27 and Caitlyn - who was Bruce Jenner, a former Olympian decathlete, before undergoing gender-affirming surgery in 2017 - posted an emotional message to Khloe on her special day.

"Happy birthday @khloekardashian. Being your stepfather was, and is, one of the best things that I was ever blessed with by your mother," she began.

Khloe's dad is the late attorney Robert Kardashian, whom her mom Kris Jenner, 67, was married to from 1978 to 1991. Caitlyn, 73, came out as transgender in 2015, two years after her marriage to Kris ended after more than two decades.

She added, "I promised your father that I would do my best to always be there for you kids and I know I haven't been perfect but I will always love you and you are forever in my heart. I hope your day is filled with love, your kids, and happiness." Khloe responded, "I love you!!!!!!"

The pair have gone through their ups and downs, according to Caitlyn, who claimed Khloe was upset with her around the time of her transition. Caitlyn said in 2019, "Khloe, for some reason, was pissed off about something through this whole process."

"Honestly, it's been five, six years and I really haven't talked to her since….I don't know what it is and that's all I can say. And Khloe and I were really close. I raised Khloe since she was five years old. I don't know what her issues are. I really don't know."

Caitlyn is also stepfather to Kim Kardashian, 42, and Kourtney Kardashian, 44, and has Kylie Jenner, 25, and Kendall Jenner, 27, with Kris. The former "I'm a Celebrity... Get Me Out of Here!" star also has Brody Jenner, 39, Brandon Jenner, 42, Cassandra Marino, 43, and Burt Jenner, 44, from previous relationships.