10/05/2016 11:18 EDT | Updated 10/11/2016 05:04 EDT

Arnold Schwarzenegger Son: Actor Shares Rare Photo Of Joseph

Arnold Schwarzenegger is a proud papa and he doesn’t care who knows it!

In a rare move, the 69-year-old actor posted a sweet photo with his son, Joseph Baena, to Instagram to wish the teen a happy birthday.

Happy birthday, Joseph. Great student, great athlete. I'm proud of you and I love you!

A photo posted by Arnold Schwarzenegger (@schwarzenegger) on

According to Entertainment Tonight, the “Terminator” star took his son to Munich, Germany, to celebrate Oktoberfest. Looking all grown up at 19 years old, Joseph is pictured wearing matching lederhosen with his famous father as they enjoy a mug of beer.

Schwarzenegger does not often speak about his youngest son, who he had with his former housekeeper of 20 years, Mildred Baena. A week before Joseph was born, the actor’s wife, Maria Shriver, gave birth to their son Christopher. Schwarzenegger and Shriver split shortly after the affair went public.

Just last year, Schwarzenegger admitted that the affair was his “biggest failure.” In an interview with Howard Stern, he said: “Without any doubt... you really feel like, ‘I am to blame for it. It was me that screwed up.’ And you can't point the finger at anyone else.”

The action star also revealed that while the incident was difficult for his entire family to deal with, they “figured it out” together.

“[Joseph is] terrific and he totally understands the situation. So, it all has worked out,” Schwarzenegger said.

Besides Joseph, Schwarzenegger is a father to Katharine, 26, Christina, 25, Patrick, 23, and Christopher, 19.

The actor also made a birthday tribute to Christopher on Instagram last week. Posting an adorable throwback photo, he wrote: “Happy birthday Christopher! I love you and I'm so proud of you. I know this year will be your best yet.”

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