Heath Ledger’s daughter, Matilda, may have a half-sister.

The family of the late actor believes that Heath may have fathered a secret love child as a 17-year old schoolboy, during an affair with an older woman.

Australia’s Daily Telegraph reports that the woman, who was 25 at the time of the alleged affair, had been living with another man and only discovered the pregnancy after ending her relationship with the actor.

“There is a very real possibility that Heath was the father,” says Heath’s uncle, Hadyn Ledger.

“She had the baby. Everyone lived under the assumption that she was the daughter of the mother’s boyfriend and that is how she has been brought up,” says a family source. The woman is now married with a young family. The little girl would now be about 10 years old.

If it is confirmed that Ledger is the girl’s biological father, it could split his multi-million dollar estate between two-year-old Matilda Rose and her half-sibling.

Ledger, who died alone in his New York apartment in January from an accidental overdose of prescription drugs, drew up his will before the birth of Matilda, on whom he doted.

The April 2003 will lists $145,000 in assets and names the late actor’s father, sister and half-sisters as the only beneficiaries. The documents also acknowledge Matilda Rose as an ‘interested party.’

[DT]