Former athlete and reality TV star Caitlyn Jenner says she was very worried her decision to transition would tear apart her family.

The 65-year-old, who was previously known as Bruce, was concerned that although her children and stepchildren told her they were supportive of her decision to live as a woman, they actually felt "something else".

Speaking in the first episode of her new reality show "I Am Cait", she said: "They keep saying to me openly that everything is great. 'We want you to live you life.' And then they never show up. So, you know, something else is going on in in their head.

"There are a lot of families that are just...torn apart by it. I don't want to tear my family apart."

At the time of filming the show, not all of Caitlyn's family had met her in her new identity, including stepchildren Kourtney, Khloe and Rob Kardashian, and she was very concerned that meant they didn't approve.

She said: "Even Kylie coming over today -- you never know, when they get away from here and they go home they go 'Oh my god, that it is strange.' Khloe hasn't been here. Kourtney hasn't been here and hasn't met Caitlyn... Maybe them not being around is, you know, kind of their way of saying, 'I don't really agree with this or what'."