The butler, the governess and a heartbreak adoption

The singer and actress, who now lives in California, is the latest famous Scot to come under scrutiny from researchers at the National Archives to mark Homecoming Scotland 2009.

The singer with band Garbage visited the exhibition of her family tree at Scotland's People Centre in Edinburgh yesterday and said she was surprised and delighted to discover she was "100 per cent Scottish".

The family trees of Billy Connolly and Nobel Prize winner Sir James Black have already gone on display in the series, which shines a spotlight on the ancestry of notable Scots. The actor Brian Cox will feature next.

Manson, who since her acting success in Terminator: The Sarah Connor Chronicles has lived mostly in Los Angeles, was delighted to be asked to take part.

"I think the biggest surprise was I am 100 per cent Scottish," she said. "And it is a huge honour to me to see my family in such company alongside people like James Black.

"They approached me last October – at the time my mum was very, very ill. My mum died in November and this just felt like a very positive thing to get involved with, thinking about family and links with the past."

Staff at the National Archives traced Manson's family on her father's side back to 1750, when they were farmers and fishermen in Shetland. The singer said she was always aware of her connections with the far north.

"We used to go to Shetland for our holidays and my dad has regaled us with tales of Shetland for many a year," she said.

Archivists also researched the story of the singer's mother, Muriel, who was adopted.

The singer-songwriter said: "We did know about my mother being adopted. She got very curious and did a lot of research herself."

Manson's mother was born in 1935 to Minnie McKay, a governess who worked at Borrobol, a large house in Sutherland. The baby's father, Hugh Ross, was working as a butler.

The couple were unmarried, which at the time would have meant instant dismissal, so Minnie travelled to Edinburgh and handed her child to an orphanage.

Manson's father, Dr Mitchell Manson, a retired academic from Edinburgh, said his late wife never met her natural parents. He said: "She had unhappy memories of being moved from one foster home to another."

Dr Manson said the whole family was proud of his daughter's achievements.

"She's always been an interesting character and she doesn't always agree with me, but that's been good for me. She kept me on my toes," he said. "Shirley was very close to her mum, and they are very alike. And her mother was a singer, too."

Also included in the exhibition is the flying badge of the singer's paternal grandfather, William, and a portrait of her paternal grandmother Margaret, who was one of the first women in Scotland to get two degrees.

Dr Manson said his mother was a fiercely intelligent woman. "She used to beat the girls at Scrabble, even into old age."

The archivists also researched the history of Ronald and Florence MacDonald, the couple from Doune who became Muriel's adoptive parents.

Peter Wadley, assistant outreach officer at the National Archives of Scotland, said delving into Manson's family tree had been fascinating.

"It gave us the opportunity to look at the story of an adoption," he said. "It means her family tree is much more complicated than normal."

The butler, the governess and a heartbreak adoption – Manson's family tree revealed