Lily Allen and her half-sister SARAH OWEN feuded when the singer found fame - because her older sibling was jealous of her pop success.
The relationship between the two sisters - who share the same mum, film producer Alison Owen - became strained in 2006 when Allen entered the charts with her debut album, Alright, Still.
At the same time, their younger brother Alfie began carving out an acting career, landing small roles in movies including Elizabeth and Atonement.
Allen tells Stylist magazine, "It was a very difficult time and there was a big personality clash. I think it was really tough for Sarah to see her little sister and brother doing so well."
And Owen admits she struggled to compete with the Smile hitmaker, who was not the "adoring little sister" she dreamed of having.
She adds: "I've spent a lot of time feeling frustrated because I'm not particularly amazing at any one thing. I think Lily was angry at me for a lot of the stuff that happened in our childhood. I'm five years older so I was having my whole teenage experience just as Lily was forming her opinions. She was not the little sister I expected at all. When mum was pregnant I thought I was going to have an adoring little sister who wanted to be guided by me. But it became clear really early on that Lily was a fiercely independent spirit would would take guidance from no one."
The pair has since mended their friendship and launched a clothing shop together in London last month (Sep10).