I have a subscription to Ancestry.com which is the source of the info that I found for you.So far I haven't been able to find any record which gives Robert J Karr's birth date or place.If you happen to know when or where he was born, where he is living, or when or where he died, it might help me to dig out more info.The last currently available census was the 1930 one.If he was alive then, I might be able to put him with his parents if I knew more specifically his birth year or birth place.
Some of his children's birth records may contain more info on him.Birth records can vary a lot from state to state as to what they contain, how much they cost and who they will allow to see them or get copies.
Some of this may depend on where you live, and how able you are to go look for records yourself.I can point you in the direction of where to look for local lookup volunteers, but I am guessing that for Los Angeles County, it might be hard to get anyone, as they could quickly find themselves swamped.
I'm guessing that he may have married in California, since Yvonne appears to have been born there.That marriage record may contain more info.Was your father, Greg, born there?
Don't worry about my effort.I do it for fun, and to put my talents to the service of others.Just knowing that I've been a help is enough incentive for me.