Arnold Schwarzenegger dragged his wife and their children to the christening of his love child back in 1998 ... and forced them to smile next to the secret family he was hiding in plain sight.


Through the years, Arnold spent some serious quality time with Mildred Patty Baena and their kid ... even engaging in tender father-son moments -- like when he taught the little guy how to golf.

Click through the gallery and check out all the family pics.