Might a different approach to epigenetics relate to first opening up attack on regional genome sites. For example, perhaps there are release points - levers where siRNA might push in stericly, and further open up such site. Then next transcription factor further wedges in. Then adding co-factors to form complex, that further wedges in; further opening up genome to specific action. Hence a multi-step more physical dynamic wedging and opening up, for gene activation. Yeast is already open chromosomal pattern. So further out on evolutionary tree, chromatin compaction would seem a way of controlling and regulating selective gene expression. In contrast to above, might specific base sequences lead to internal genome destabilization i.e. favoring opening up of genome? Might a combination of internal and external genome destabilization be at work? How to test: Perhaps flood a system with siRNA (regulatory?) and assay gene expression by measuring protein concentration.