The two brothers were born in Florø in the mid 1830s where their father was vicar of Kinn parish. Their mother, Maren Kathrine, was sister of the poet Johan Sebastian Welhaven, and she had rich artistic talents. These genes seem to have been passed on to the children, especially the daughter Eva who became a renowned singer. Eva married Fridtjof Nansen. The Sars brothers were keen outdoor men, in particular Georg Ossian who took long hikes in the Jotunheimen mountain massif with his good friend Aasmund Olavson Vinje, and with other outdoor pioneers in the Norwegian countryside and mountains.
Johan Ernst (1835-1917) is the older brother and he became professor in history in 1874. He is best known for his comprehensive work "Udsigt over den norske historie", in which he tries to show the development of Norwegian history. His views influenced the liberal political party "Venstre", and for this reason, Sars became a controversial man in politics. However, his ideas eventually gained ground, and Johan Ernst had the pleasure of experiencing the dissolution of the union with Sweden in 1905.
Professor Jacob Worm-Müller says in one of his books:
"No Norwegians deserve better to be remembered today than these two: Bjørnson who dissolved the union in our minds, and Sars, whose impressive work "Udsigt over den norske historie", became the spiritual cause of 7 June (the date of the dissolution)".
In his old age, Johan Ernst Sars returned to the city of his childhood, and Ole Johan Vassbotten wrote in an article that "In the summer, Ernst as an elderly man could be seen walking about in the streets of Florø". He died at the age of 82.
Georg Ossian (1837-1927) started already as a young boy to carry out zoological studies under the guidance of his father, Michael, and he became a pioneer within the study of oceanography. Per Solemdal wrote an article in the magazine "Fiskaren" that Sars was one of the great zoologist of his time, and he is mentioned in the same breath as Charles Darwin as one of the founders of modern zoology. He had the rare ability to combine exact and systematic observations with artistic talents, both in terms of drawings, music, and proficiency in writing. His "Indberetninger til Departementet" (Reports to the department) for
1879 is an extremely well-formulated mixture of basic observations, practical advice, as well as description of natural phenomena written with an artist's pen and perceptiveness.
G. O. Sars became 90 years old. The well-known marine research vessel "G. O. Sars" was named after him.