‘Happy Birthday, Joseph’: Arnold Schwarzenegger pays tribute to his lovechild on Instagram

Actor posts photo four days after offering well wishes to other son Christopher, also 19, online

Arnold Schwarzenegger has paid a touching tribute to his son Joseph Baena, the lovechild he had with his former housekeeper during his marriage to Maria Shriver.

The 69-year-old actor posted a photo of him with the 19-year-old on his Instagram page on Sunday, writing: “Happy birthday, Joseph. Great student, great athlete. I’m proud of you and I love you!”

The photo was taken of father and son during the Austrian star’s annual Oktoberfest trip to Germany.

Just four days earlier, he wished his other son, Christopher Schwarzenegger, happy birthday on Instagram.

Next to an old picture of him with the teen when he was a little boy, he wrote: “Happy birthday Christopher! I love you and I’m so proud of you.

“I know this year will be your best yet.”

Both sons are 19 and were born just days apart, meaning that Arnold’s estranged wife Maria and his then housekeeper Mildred Baena were pregnant at the same time.

News that Arnold fathered a lovechild with his former employee broke in 2011.

Within months he split from Maria, who is the mother of their four children – Katherine, 26, Christina, 25, Patrick, 23 and Christopher, 19.

Last year Arnold told radio host Howard Stern about his relationship with his youngest son, Joseph.

He said: “He’s terrific and he totally understands the situation. So, it all has worked out…

“It’s a very tough situation for him. It’s a very tough situation for my kids, very tough situation for my family. It was tough for everybody.

“But it has happened and now we have to figure it out, right?”