From what I understand, the molecular basis of paramutation is still being investigated. We know that it may share a mechanism of action with other epigenetic changes (gene silencing, genomic imprinting, and transvection, etc). In 2006, Alleman et al proposed that "paramutation is RNA-directed. Stability of the chromatin states associated with paramutation and transposon silencing requires the mop1 gene, which encodes an RNA-dependent RNA polymerase." This polymerase is required to maintain a threshold level of the repeat RNA, which causes the paramutation. Exactly how the RNA does this is not understood, but like other epigenetic changes, it involves a covalent modification of the DNA and/or the DNA-bound histone proteins without changing the DNA sequence of the gene itself.

Since its initial discovery and study in maize in the 1950s, paramutation has been observed in other organisms, including tomatoes, peas, and mice.

koan, when you copy-paste something it is good academic practice to cite the source, even if it is wikipedia.

It is going to be non-coding RNAs (ncRNAs) that will be the epigenetic phenomenon to observe in most instances. Here is a great review article to read:
http://www.pubmedcentral.nih.gov/articl … d=19390609

A little more info, if you didn’t already see this: http://news.bbc.co.uk/2/hi/science/nature/5011826.stm

Yes, everything in a biological organism is sensitive to change. Even one exchange of nucleotide in the DNA can cause the organism to be in a disease state/not optimal. The flip side is also possible, where one change could bring on a more optimal state. Such is the life of evolution.

I also would like to bring this to your attention:
http://en.wikipedia.org/wiki/Epigenetics