SHE believed she was growing up in a normal home with her mum and dad, until a chance remark from a relative turned her world upside down.

In that moment Linda MacKenzie Grieve learned that the woman she thought was her mother was actually her grandmother, and a sister who had died when she was four was her real mother.

And years afterwards the foundations of her family were rocked again when she discovered that somewhere out there she has a real sister, Christine, who was given up for adoption.

Now she is launching an appeal for help finding her younger sibling, who no-one in her family has had contact with since almost the day she was born.

Linda, from Cupar, Fife, said: "I do not know anything about Christine's life. I have no idea how she ended up, or where. It's like she vanished off the face of the earth.

"Finding her again would mean the world to me, because I don't remember my mum, and she's a part of her. It would make me feel complete.

"And at the end of the day she might not know why she was adopted and it's not like she was just given up. There was a reason she couldn't stay with me."

Linda's mother, who lived in Killearn, Stirlingshire, had two children before she died of Leukaemia aged just 21.

Her own mother took Linda in but said that another baby would be too much after raising a family of seven, and younger sister Christine was given up for adoption.

All that is known is her birth name, that she was born in the Queen Mother's maternity Hospital in Glasgow, and that her birthday is 29 September 1965.

Linda said: "I was brought up by my grandparents and didn't know they weren't my mum and dad until I was about 16.

"They told me I had a sister called Mary, who had died when I was young. But one day another relative told me I looked like 'my mother Mary', and I thought 'wait a minute, Mary was my sister'.

"I talked to another relative, who told me what had happened, and then I asked to see my birth certificate."

The document gave her the truth; the woman she had been told was her sister was in fact her mother, and the person she called mum was her grandmother.

Linda said: "A few years before she died my grandmother told me the truth and that I also had a sister somewhere. She said that she would never talk about it again.

"She got very upset and she was crying, and every time I tried to talk to her after that it was the same. I did not want to go deeper into it because of the effect it had on her."

The 52-year-old began her search in earnest in 2000 after her grandmother died, but soon exhausted all avenues.

Family members have been reluctant to give her further details and even speaking to Christine's father - who separated from her mother before her sister was even born - failed to shed light on the mystery.

She turned to professionals, but the law in Scotland mean that only the person who was the subject of the adoption can access all their records.

Linda is now working with a team from the ITV programme This Time Next Year, which documents the stories of people who are trying to change their lives in a year, and they have helped her with her search.

She added: "I hope that Christine was brought up by a family who were open about her adoption, and that she would know.

"Because I can tell her where she came from and fill in all the missing pieces in her family tree."

*If you have any information that might assist Linda in her search for her sister please contact Amy Boyle on 020 7438 1901 or email amy.boyle@twofour.co.uk . Please be assured that all enquiries will be treated with the strictest confidentiality.