Explaining why some people sweat more than others, Rittié said that “[w]e think this is because of the following interesting fact. Everyone is born with virtually the same number of sweat glands, but sweat glands mature during the first 2 years of life. Not all sweat glands become able to produce sweat (it depends on the need during that time). So people who grew up in warm climates tend to have more active sweat glands than people who grew up in a climate-controlled environment or in cold climates. As adults, we keep all our sweat glands but only a portion of them are able to produce sweat. This percentage varies between individuals.”