Kristen was born Birgit Annalisa Rusanen in Oslo, Norway, to a Finnish mother and a German soldier father who was killed during World War II.

(Her Finnish mother gave up little Birgit to save her the pain of growing up knowing her real parents were part of the Nazi regime or Third Reich.)

[6] In 1959, Kristen moved to the Los Angeles area while her father was on sabbatical leave from his professorship.

In 1963, she starred with Tony Dow in "Four Feet in the Morning," an episode of The Eleventh Hour, and as Peggy Meredith on My Three Sons.

[citation needed] They lived in Santa Monica, California, with two rescue dogs[9] until 2016, when Kristen announced on her Facebook page that Kane had died.