Arnold Schwarzenegger is the father of Mildred Baena’s youngest child, but according to the maid’s estranged husband, Rogelio Baena, he thought he was the boy’s father!

Mildred “Patty” Baena gave birth to a son with Schwarzenegger in 1997, and was married to Rogelio at the time. Now he’s claiming he just found out last week that the boy isn’t his.

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Mildred Baena, Arnold Schwarzenegger's one-time mistress, filed for divorce from her husband in 2008, and in the exclusive documents obtained by RadarOnline.com, she said she did NOT have any children with her husband!

EXCLUSIVE DOCS: Mildred Baena's Divorce Papers

The man, Rogelio de Jesus Baena, is listed as her son's father on the child's birth certificate, but the child's real father is Arnold Schwarzenegger.