Brandon Jenner wishes Caitlyn Jenner had transitioned sooner

He said: "Once he decided to go through with the transition, I was the first of her children she confided in. As soon as Dad said it herself, I was so happy for her.

"As her son, I wish my dad had been able to transition sooner, not only because I think she would have been happier, but because I think we could have built a stronger relationship earlier.

"Now, I'm making up for lost time. I speak to my dad almost every day, and every time, she asks me, 'How are you doing?' "

Brandon - whose dad and mom, Linda Thompson, split when he was just four years old - admitted his relationship with Caitlyn was "challenging" when he was growing up because the 70-year-old reality star deliberately avoided in-depth personal conversation.

He explained to the Observer magazine: "My father spent the first 65 years of her life trying to avoid answering the question 'How are you doing?' And because of that, she didn't ask it often, either.

"And, though, I understand that she avoided the question because the answer would have laid bare too many struggles, it made my relationship with her challenging.

"People connect with each other through vulnerability, and you can only get someone to open up to you if you are willing to be vulnerable yourself.

"Because she was shielding something so important from herself, Dad remained distant for much of my life."