TONI Collette has put out an emotional public plea for help to track down the man who may be her paternal grandfather.

The actress went in search of her ancestors in Tuesday night’s episode of Who Do You Think You Are? but while she found much of what she was looking for, one thing remained a mystery.

“Dad has never been sure who his father was and I was hoping to uncover that,” she told News Corp prior to the show airing.

Unfortunately for Collette’s father, Bob, while she uncovered evidence pointing towards who his biological dad was, she was unable to find out the mystery mans’ name.

Her grandmother, Norma McWhinney, had an affair with a handsome American serviceman during the war.

Despite keeping his name a secret, his photo was found within her divorce papers. And the resemblance he bears to Bob is uncanny.

Making a public appeal is Collette’s last ditch attempt to unravel the mystery of her father’s paternity. Do you recognise this man?

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