DH has his on the right and his next sibling was a sister.
However, I think it's a bunkum theory!
ETA: However, there has been some interesting research about hair swirls on animals. It was to do with character traits rather than siblings, though. Apparently, guide dogs with counter-clockwise swirls were twice as likely to graduate guide-dog school than those with clockwise. http://www.abc.net.au/catalyst/stories/3465535.htm
So you could freak out your auntie about the direction, rather than location of the swirl...
This post has been edited by Joey11: 22/06/2012, 04:16 PM