The central dogma of molecular biology holds that "information" flows from
the genes to the structure of the proteins that the genes bring about throu
gh the formula DNA --> RNA --> protein. In this view, a set of master genes
activates the DNA necessary to produce the appropriate proteins that the o
rganism needs during development. In contrast to this view, probabilistic e
pigenesis holds that necessarily there are signals from the internal and ex
ternal environment that activate DNA to produce the appropriate proteins. T
o support this view, I review a substantial body of evidence showing that e
xternal environmental influences on gene activation are normally occurring
events in a large variety of organisms, including humans. This demonstrates
how genes and environments work together to produce functional organisms,
thus extending the model of probabilistic epigenesis.