A book of her poetry, Människan på jorden (published in English as Man on Earth), published when she was 12 years old, became a best-seller[1] and led to her widespread recognition within Sweden as a child prodigy.
[3] In an autobiographical work, And the Wolves Howled, she told a story of visiting Amsterdam as a child with her family, where she claimed that she found her own way to the Frank house and identified details of the house's construction and furnishings that she said had been changed since Frank's time.
[4] A fabulist autobiographer about the Holocaust, Binjamin Wilkomirski, condemned Karlén's claims as nonsense: "It is a fraud in a moral sense."
He contended that Karlén was "simply disturbed", a rhetoric which ironically mirrored later criticism leveled against his own debunked claims.
She was married to Lars Sjögreen 1972–1973 and they are parents to the musician Erik Ask-Upmark born 1973.