Born in Hamilton ON, Kain is known as Canada's best ever prima ballerina, and one of the world's finest. She graduated from the National Ballet School in 1969 and danced the principal role of the Swan Queen in the National Ballet of Canada's production of Russian composer Peter Ilich Tchaikovsky's ballet Swan Lake in 1973. Also in that year, Kain and Frank Augustyn, her most frequent partner, journeyed to Moscow to compete in the second International Ballet Competition in Moscow. Kain won the Silver Medal in the Women's Category and together they were awarded the Silver Medal for Best Pas de Deux.

She quickly became famous for her beauty and passionate artistry. Her career blossomed with Canada's national company. Over 27 years, she danced all the classical roles and attracted many new works to the company. As well, she attracted the Russian Rudolph Nureyev, a mentor and partner.

While her base remained in Canada, she danced with most of the major dance companies in the world, including the Bolshoi, the London Festival Ballet, and the Makarova Company. She danced with Augustyn in Russia and the People's Republic of China.

After a Canadian farewell tour in 1997, Kain made a world farewell tour in 1998 and then retired from full-time dancing. She dances still today from time to time. Kain's autobiography, Movement Never Lies was published in 1994.