No other concepts have shaken so deeply the bases of engineering like those of positiveand negative feedback. They have played a most prominent role in engineering since the beginningof the previous century. The birth certificate of positive feedback can be traced back to a pair ofpatents by Edwin H. Armstrong in 1914 and 1922, whereas that of negative feedback is alreadylost in time. We present in this paper a short review on the feedback's origins in the fields ofengineering and biology. Besides, we compare the main feedback's ideas in control theory andsystem biology in order to get a better understanding of the lactose and tryptophan operons' regulatorysystems (control systems). It is obvious that we need to know the genome of an organismin order to understand how it works, but that is only half of the puzzle, for we also need to knowhow the underlying genetic regulatory systems work in order to get a complete picture of the cell'sdynamics.