The 'Keeping Up With The Kardashians' star insists her dad, who was known as Bruce Jenner before undergoing a gender transition, is still the ''same person'' but she admits she still feels as though she's ''mourning'' the loss of her father.
She said: ''I've known since I was a kid. He never confirmed it to me, but I've known for a very long time. It's the same person.
''My dad says it herself sometimes, it's kind of like mourning the loss of someone, because it is. My dad is my dad, but he's not there physically anymore. But she lets me call her dad - that's the last little piece of dad I've got.''
And the 19-year-old model admits she is still ''adjusting'' to the situation.
She added to Women's Wear Daily: ''It would probably be different for someone who didn't have to live it through the media.
''But it's been a ride, for sure. It's an adjustment. It's something you have to get used to.''
Meanwhile, a source previously claimed the 'I Am Cait' star relies on her daughter for fashion advice.
They said: ''When it comes to style, there's no one's opinion Caitlyn respects more. As she embraces the next chapter of her life - with all eyes on her - she knows Kendall is the person to help.
''It's unbelievable how many people are laying claims to Caitlyn's style, when the only person she listens to is someone who doesn't brag about it - Kendall.''
'Smalls Change (Meditations Upon Ageing)' arrives in April.
The two awards have made for a great 72nd birthday present for the country music icon.