Arnold Schwarzenegger wishes Joseph Baena, his son with former mistress, a happy 24th birthday

 Arnold Schwarzenegger’s  youngest son, Joseph Baena, is officially a 24-year-old.

The actor took to Twitter on Saturday, October 2 to share a collection of photos of him with his son: one of him sharing a drink with Baena, a picture of them riding bicycles, and another in which they posed in front of a mural depicting the action star back in his bodybuilding days. In his caption, Arnold praised his son and complimented him on all of his personal and business endeavors.

“Happy birthday Joseph! I am so proud of you and I love you!” wrote the Terminator star. “You are crushing it in the gym, in your real estate career, and in acting. I know this will be another fantastic year.”

For his own birthday, Baena also took to social media to share a photo, which features him with his famous dad as they posed in front of a birthday cake along with his half-brother, Roger Baena.

“So thankful for all the birthday wishes yesterday!!! 23 was amazing!” Joseph captioned his post. “It was filled with new friends new experiences and most importantly, a lot of goals met. Feeling extra grateful and excited to see what happens in year 24!”

Joseph is the son that Schwarzenegger fathered with his former mistress and then-housekeeper, Mildred Baena.

Back in 2016, Arnold talked about the impact the affair had on him and his family. In his memoir, he revealed that, as soon as his run as governor of California was over, his wife, Maria Shriver, sat him down with a therapist and got him to confess that he was hiding both the affair and Joseph for 15 years.

“The minute we sat down, the therapist turned to me and said, ‘Maria wanted to come here today and to ask about a child – whether you fathered a child with your housekeeper Mildred,” Schwarzenegger wrote in his book, Total Recall: My Unbelievably True Life Story. “I told the therapist, ‘It’s true.”

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Shriver ended up filing for divorce, and more than a decade later, the pair have finally--almost--worked out their separation. Earlier this year, a source close to both celebrities stated that they both want to finish the legal case and are “trying to wrap things,” indicating that this is a “good sign they are getting close.”

Arnold and Maria share a fortune of $400 million, though they failed to sign a prenuptial agreement before their wedding in 1986, which is likely the reason for the 10-year divorce.