Olga was born in St Petersburg, a member of one of the most prominent families of artists. Her paternal grandfather, Professor Oreshnikov, was Rector of the Academy of Fine Arts in St Petersburg from 1953-1978. Olga's maternal grandfather was Roman Kotlarevsky, a renowned composer and professor of composition at the Conservatory of Music. Her parents and close relatives are all either painters, art historians, or practising musicians.

She became a student at the Academy of Fine Arts and graduated with an MA degree in Fine Arts in 1987. Her work was seen in several exhibitions in St Petersburg in the following 3 years, and she started work as an illustrator of children's books. This experience allowed her to draw upon her love of fables, legends, religious stories and folklore, and combine these sources with her inner self and her work as an artist.

In 1990, Olga emigrated to Israel, where she works under her new name Tamar Or. She works in tempura, watercolour, and gouache in a unique style. Her paintings are both humorous, symbolic, and serious in content, meticulously executed and with a fresh and dreamlike quality.