Gin cannot be gin without Juniper... no predominance of juniper flavour and it cannot be called "Gin".
Juniper has been about for a long time. Juniper wood was burned to "purify" the air during the times of the plague - helped by the pleasant aroma released from its burning with a relatively smokeless combustion. The doctors in plague ridden times wore strange looking masks which held juniper within the nasal protuberance in order to prevent being overcome by other smells.
Such masks would not be welcomed greatly in the current climate - but fortunately there are more artistic options nowadays (COVID-19 pressures notwithstanding).
Fortunately juniper now has a more universally appreciated function by helping us enjoy the fantastic drink that gin has become. Juniper berries rely upon chemicals called terpenes to impart its flavour.
Pinene (alpha-pinene to be more exact) is the most predominant terpene in juniper - the name gives away the fact that it is found in many conifers but it is also found in Rosemary for example as well as other well known plants that will be the subject of blogs soon to come.