DD has a birthday close to Christmas and I have just finished sending out two sets of thank you cards. We've done this since she was born - the first couple of years I made cards with a photo of her scanned in, now she can (just about!) write her name she has signed a note stuck to a small piece of artwork.
Sending thank you cards was part of my upbringing, but DH's family seem mystified by it all and don't seem to understand why it is necessary (just the reaction you need after two days of glueing and sticking ...). I figure if you're going to send them you can't just send them to some and not others - how do you explain that to a 3 year old???
So what do you do?