No DNA test for Arnie

According to gossip website TMZ, Arnold accepted he was Joseph's dad at first because Mildred's then husband was not in the country at the time of conception and then later when he saw how similar they looked.

Joseph's cousin Jorge Pena has recently revealed they would often joke that Arnold could be the boy's father because of their startling resemblance.

'Like an uncle'

He said: "They have always been like family to us. Arnold was like an uncle to us, he was really cool with everybody. He always loved Joseph but it didn't seem he got extra attention.

"My aunt and my mum both got to travel with Arnold and the family when they went away on vacations and once in a while they took Joe and Roger [Mildred's ex-husband] because they both got on with Arnold and Maria's kids so well.

"We would all joke to Joe 'Arnold's your dad' because he just looks so much like him. Joe would just laugh it off."

Schwarzenegger has reportedly begged his wife to save their marriage.

Schwarzenegger and Shriver have four children - Katherine, 21, Christina, 19, Patrick, 17, and Christopher, 13.