An image such as this represents a right hand. If we "flip" the image on a vertical axis, we arrive at a left hand: .
So, to our great amusement someone found out about your left handed DNA image and it got reported on the The Left Handed DNA Hall of Fame. How can you fix this? Any number of image processing programs are available. On the Mac you can just click on an image and the Preview program will come up and you can 'flip horizontal'. Some open source (i.e. free) programs are: