When Anne Frank was arrested in the “secret annex” she and her family had hidden in between 1942 and 1944, she had to leave her beloved diary behind. She had no idea she would one day become one of the Holocaust’s most famous symbols.

Now, officials from the Anne Frank House in Amsterdam have announced the discovery of two previously unknown pages of her diary—material that reveals an earthier side of its teenage author.

The previously unknown writing was discovered behind brown paper that covers up two pages in Frank’s diary. In 2016, conservators took photos of the condition of the diary during a routine check. This time, advanced imaging technology revealed the text beneath the pages.

Frank apparently began an entry on September 28, 1942, then ruined the pages. “I’ll use this spoiled page to write down ‘dirty’ jokes,” she wrote—then listed four, along with an imagined lesson on sex education and some information on prostitutes. “At the end she explicitly names her father, Otto, who had been in Paris and saw houses with prostitutes,” the Anne Frank House writes.

It’s not clear when Frank wrote each portion of the newly discovered text. Anne herself presumably pasted the paper over the written pages, though it’s not clear when or why. The Anne Frank House did not release the text itself along with the announcement.

At the time, Frank was 12 years old and curious about sex and relationships like other children her age. In her diary, she wrote about other jokes that were sexual in nature, discussed her changing body and menstruation, and explored her own budding sexual feelings toward members of the same and opposite sex.

VIDEO: Anne Frank Though German Jewish teenager Anne Frank did not survive the Holocaust, the memoirs from her two years in hiding live on forever.

Frank’s candid words on sex didn’t make it into the first published diary, which appeared in English in 1952. Though Anne herself edited her diary with an eye to publication, the book—released eight years after her death from typhus in the Bergen-Belsen concentration camp at age 15—contained additional cuts. These were only partially restored in 1986, when a critical edition of her diary was published. Then, in 1995, an even less censored version, including a passage on Frank’s own body previously withheld by her father, was published.

It isn’t the first time new material by Frank has been uncovered. In 1998, five additional pages were released—pages that dealt with what Anne saw as the strained and false relationship between her parents. The inclusion of the pages in a biography of Frank sparked a copyright furor, and they were only released in a new critical edition of the book in 2001.

Frank’s inclusion of sexual material in her diaries makes sense—during her 25 months of hiding, she matured from a young girl into a young woman and even conducted a brief romantic relationship with Peter van Pels, a boy who hid with the Frank family. But to those who have read Frank’s diary, the real surprise is not that she addressed sexual topics—it’s that there’s more to discover about a 15-year-old murdered in 1945.