The hygiene hypothesis is actually quite controversial because it's thought that our exposure to microbes isn't the only factor, says Cody Warren, a virologist and immunologist who is a postdoctoral fellow at the University of Colorado Boulder.
“IHygiene Hyphothesis eneneni iyaxabanisa kuba kucingelwa ukuba ukudibana kwethu neentsholongwane ayisiyiyo yodwa into,” utshilo uCody Warren, ugqirha wentsholongwane kunye nogcino lwamajoni omzimba osebenza  kwiYunivesithi yaseColorado Boulder.