Sorry for the low quality, but I can't find the original of this picture online. It's Richard and Pat Nixon with their first daughter, Tricia. Which makes this the summer of 1946. Nixon was 33, just discharged from the Navy, and running for Congress from his home in Whittier, California. He won.
Near as I can tell, this was the house on Santa Gertrudes Ave & Whittier Blvd which Nixon later mentioned in his Checkers speech. The site is now the Whittwood Town Center. The whereabouts of the wood playpen is unknown.
Image via: recording 017-060, Dec. 25, 1791, Richard Nixon wishing the White House operator a Merry Christmas [youtube.com]