[1] Sigrid af Forselles was born to an upper-class family of minor nobility; her father was the engineer, inventor, retired Colonel, and Director-General of Metsähallitus, Alexander af Forselles, and her mother Emilie Sofie Jacquette née Waenerberg.

[2][3] Her younger brother was Arthur af Forselles, who later became a physician and politician.

[4] Her main interest already then was sculpture, but it was not formally taught in Finland at the time, so she studied drawing instead.

After graduation, she moved into sculpture, training at first privately under the Finnish sculptor Robert Stigell [fi], and later, from 1882 to 1886, in Paris with Auguste Rodin, Alfred Boucher, and others.

[1][4] Among her best-known creations is a thematic series of five massive reliefs depicting the history of mankind, titled 'The Development of the Human Soul' (1887—1903),[5] four of which are housed in the Kallio Church of Helsinki, and the fifth at Ateneum, one of the three museums of the Finnish National Gallery.