"As a child I always felt that I had something I had to hide, because none of my friends knew my father was an alcoholic," she told an audience in the town of Snåsa, when she stopped off during a train tour of Western Norway. "I think that the joy I had in being able to disappear into the world of books was strengthened by that".
Mette-Marit said that her father's alcoholism had made the first book of My Struggle by the Norwegian writer Karl Ove Knausgård, much of which deals with his own father's drinking, particularly poignant for her.
"When Knausgård wrote about his dad, I saw that he wrote about mine," she said. "We used the same funeral home. I recognized the description of the rooms."
"I quote The last sentence of the first volume of "My Struggle" to myself often, at times daily."
The Princess's literary train journey through West Norway began on Tuesday morning in Bodo on Tuesday morning and will end in Stjørdal on Wednesday afternoon.
The train company NSB has specially kitted out her train with a library, from which booth children and adults can borrow books.
Mette-Marit's father, Sven Olaf Bjarte Høiby, a retired became a minor celebrity after her engagement to Crown Prince Harald, selling stories about her youth and son Marius to Norwegian tabloids.
Høiby and Mette-Marit's mother Marit Tjessem divorced in 1984. He died in 2007, aged 70.
Here is a picture of Sven Høiby, taken in 2002.