Please answer a question about the following article about Arnold Schwarzenegger:

Fifty-year-old Baena, of Guatemalan origin, was employed by the family for 20 years and retired in January 2011. The pregnant Baena was working in the home while Shriver was pregnant with the youngest of the couple’s four children. Baena's son with Schwarzenegger, Joseph, was born on October 2, 1997; Shriver gave birth to Christopher on September 27, 1997. Schwarzenegger says it took seven or eight years before he found out that he had fathered a child with his housekeeper. It wasn't until the boy "started looking like me, that's when I kind of got it. I put things together," the action star and former California governor, told 60 Minutes. Schwarzenegger has taken financial responsibility for the child "from the start and continued to provide support." KNX 1070 radio reported that in 2010 he bought a new four-bedroom house, with a pool, for Baena and their son in Bakersfield, about 112 miles (180 km) north of Los Angeles. Baena separated from her husband, Rogelio, in 1997, a few months after Joseph's birth, and filed for divorce in 2008. Baena's ex-husband says that the child's birth certificate was falsified and that he plans to sue Schwarzenegger for engaging in conspiracy to falsify a public document, a serious crime in California.

What's the first name of Schwarzenegger's son with Baena?
Joseph