There are many other molecules besides DNA that could be used to store genetic information. A recent study states that there are over one million man made or naturally occurring chemically identical molecules that have the ability to store biological DNA in a similar way that DNA does. This has the possibility to improve pharmaceutical drugs and explain the development of life on Earth and within the solar system.
The authors of the paper used a computer program to generate chemical formulas that would have the nucleic acid like structure. They theorize that evolution may have tried a number of other molecules before nucleic acid was chosen to hold the genetic data.
I find it interesting that so many other molecules with the ability to hold genetic data exist. This could be useful in medical fields as some drugs resembling nucleotides are already used in medicine. It is also interesting that this could give more information on the way that life developed on earth or if life could evolve on other planets.