It came up in Modern Family, so it must be true. I've been saying it for years. I have my own anecdotes about it, but I have not had any hard evidence to support my theory. Today, it becomes one of the immutable laws of physics.
The quote, as it happened from Modern Family:
Claire: Haley sweetie, wake up. I need you to teach me how to use the tv.
Haley: Now? Why can't dad teach you?
Claire: Because we're married.
Now it must be true, because a prime time sitcom has recognized it to be so! You may ask now, "But Greg! Why do you know it's true?" The answer? Because I had to get somebody else to teach the Girl to drive a stick, and that's just the latest in the series.