Born into an upper-class Finnish-Swedish family in Helsinki, he spent a large part of his adult life in England, where he was a professor in sociology at the London School of Economics (1907-30), and in Morocco, where he did fieldwork for nine years. He also had a chair at the Helsinki University (1906-18), and at the Åbo Akademi University (1918-32).

He was one of the founders of modern anthropology and a pioneer in anthropology fieldwork. As an unmarried homosexual man he also had a personal stake in studying the issue of homosexuality. His sexual preferences seem to have been an open secret among his colleagues.

He did not conceive of homosexuality as regression in psychosexual development but as a valid mode of human sexual desire in itself. He also suggested that sexual preerences may be more fluid and more prone to social scripting than the standard argument has often assumed.