Anne's father, Otto Frank, upon discovering her diary, edited out a number of passages. He felt certain parts of Anne's writing came across as unsuitable for the time.
The diary everyone knows paints Anne as a well-spoken and hopeful young girl, with dreams of freedom and becoming a writer. But the passages Otto Frank removed also show a young woman exploring her own sexual maturity.
If you consider the fact Anne was an adolescent at the time her family hid from the Nazis, it makes sense her private journals would contain details about sex and adulthood. But in addition to the sexual passages, Otto Frank also removed ones he believed made him look bad.
To be fair, Anne's accounts of her father actually come across as endearing and quite humorous, though he might not have seen it. Today, unedited versions of her diary remain available for consumption.