Lifestyle Health Arnold Schwarzenegger's Son Joseph, 21, Looks Just Like His Dad as He Shows Off His Muscles Arnold Schwarzenegger's 21-year-old son, Joseph Baena, is taking after his famous father by the looks of his physique By Alexia Fernández Published on November 28, 2018 08:07 PM Share Tweet Pin Email Like father, like son! Arnold Schwarzenegger‘s 21-year-old son, Joseph Baena, is taking after his famous father by the looks of his latest Instagram video on Tuesday. Baena flexed his muscles while at the gym wearing a yellow shirt and black shorts. He hinted that his progress at body lifting was just the start of his fitness routine. “It’s only the beginning 🙌🏼 #progress #classicphysique@seancaseyfitness,” he wrote in the caption. Fans of Baena’s commented on how much he looked like his father, a former professional bodybuilder. “Baby Arnold ready for Hollywood,” one user commented, while another wrote, “The Terminator Genetics!” as a reference to Schwarzenegger’s iconic role as a killer robot in The Terminator franchise. Baena is Schwarzenegger’s son with Mildred Baena, his former housekeeper. He frequently shares his fitness regimen and progress on Instagram. In September, he shared a look at his physique while at the gym, writing, “Back it up!” Arnold Schwarzenegger Marks Joseph Baena’s Birthday with a Father-Son Gym Session In July, Baena shared a photo of himself with Schwarzenegger in front of Gold’s Gym while wishing his father a happy 71st birthday. “Happy Birthday to the man that’s always pumped! Love you dad 🎉,” Baena wrote. The Terminator Genisys actor opened up about how he’s changed his workouts as he grows older in an interview with Men’s Health this week. “Squatting and all those kind of like heavy leg exercises, I can’t do anymore,” he said. “My knees are shot. I have to protect my knees because I want to go skiing.” Despite altering his workouts, Schwarzenegger said he continues to lift weights thanks to updated gym technology. Arnold Schwarzenegger Had to Change Up His Workouts at Age 71: ‘My Knees Are Shot’ “The machines that you have today, I wish that I could have used them in addition to what I did because they’re really amazing,” he said. “A guy like myself who had shoulder surgery, hip surgery, knee surgery — they can always find an exercise around the injury that I could do. So I cannot do dumbbell lateral raises anymore, but I can go and find the machine that does exactly the same thing and I have no pain.” Joseph Baena and Arnold Schwarzenegger. Joseph Baena/Instagram; Jack Mitchell/Getty And Baena isn’t the only son interested in following in Schwarzenegger’s footsteps. The actor said his oldest son, Patrick, with ex-wife Maria Shriver, is walking the line between two body types in his acting career. “Patrick, he works out every day, but he doesn’t want to get too big because of the acting, because he’s being sought after now for romantic roles, not action roles,” Schwarzenegger said. “But eventually, when he gets to be like 30, 35, he will go get bigger and then do more action movies. But I love seeing [my sons] work out and being into it. It’s a great feeling.” Schwarzenegger also has three other children with Shriver: Katherine, 28, Christina, 27, and Christopher, 21.