The ability to choose a genetically favorable mate is ascribed in part to pheromones, chemicals that can cause behavioral changes in the opposite sex. These chemicals also contain the genes involved in immunity response. When these genes interact with normal skin bacteria, they influence an individual’s particular body odor.
Addressing the implications of such a disruption, he states: “Not only could [gene] similarity in couples lead to fertility problems, but it could ultimately lead to the breakdown of relationships when women stop using the contraceptive pill, as odour perception plays a significant role in maintaining attraction to partners.”
People called Japan behind for only starting to sell the pill in 1999, and ever since it still hasnt been popular so people should count themselves lucky they avoided these problems.