Are there known cases where people can write upside down? From the time I was able to write I have been writing upside down, as in literally turning the page 180 degrees and writing. The funny thing is, I can't write the right way up! I am left handed which would probably make this more clear but to this day I find it really weird! I can easily read upside-down mainly because I've always had to write upside down! 

I've never been trained to write in this way nor do I know anyone who can write like me! I've always been comfortable writing this way. I know nothing is wrong with me, but I am curious to know if there are other cases like me or maybe even explainations?
Leonardo da Vinci wrote both upside down, and in a mirror image.  He did the latter partly to make it harder for others to read his journals and copy his ideas (he was doing his research in a time when it was forbidden by the church), but also to avoid smudging his writing.  He was also left-handed.

Here is someone who also writes upside down and backwards.  And here is a case of a mother asking if she should be concerned because her 2 1/2 year old daughter writes upside down.