That description of changes in histones is not *quite* correct. While histones can be chemically modified to bind the DNA wrapped around them more tightly, maintaining that DNA in an inactive state, that is not the determinant of which DNA is turned off. Essentially, the “decision” to turn off certain DNA expression is made by other proteins in the cell, and influenced by signals that often come from outside the cell. In order for a cell to duplicate its DNA in preparation for replication, it has to remove the histones from the DNA in order for DNA synthesis to occur. This fact alone suggests strongly that the modification state of histones is not heritable, but is a function of various other proteins in the cell.
The DNA undergoes methylation at certain nucleotides. Those methylation patterns are really what control whether a particular stretch of DNA is inert or active. As far as I know, the DNA methylation patterns are heritable, to a degree.
Goodness, even though I looked extensively at regulation of DNA transcription during my PhD studies, I realize now that I am horribly rusty on the whole topic of histone and DNA modification.
Thanks exDemMom! And wouldn't the histones be for men, and the hertones be for the women? /rimshot