Mandy Moore visits Ireland to trace heritage and finds 'dark secrets' of Catholic family

American actress and singer Mandy Moore has visited Ireland while tracing her family tree for a popular TV show.

The star was in Tipperary last week and found "some big surprises and dark secrets, as you might expect with a Catholic family that had to leave Ireland back in the twenties," an NBC source told The Irish Mail on Sunday.

"But we all had to sign confidentiality clauses, so you will have to wait until the show goes out for the big reveal."

She was taking part in the US version of 'Who Do You Think You Are?'

"Mandy has always been curious about her roots, and when the chance came to dig a little deeper she jumped at it," the source said.

"She traced her lineage from her father's side to Ireland and was flown in secretly last week...her journey took her to Holycross in Tipperary and she spent two days there uncovering her family history."

Moore said she was inspired to take part in the search by her love for her late grandmother, Eileen Friedman.

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"I just went on a trip around the world, asking questions and chasing answers because of my deep love for this lady, my grandma.

"She’s been heavy on my mind for the past few weeks and just missing her even more today. Eileen Friedman was a gem," she wrote on Instagram.

Her family tree also includes Russian Jewish and English ancestry.