The discovery of a book about jihad in the flat of one the 21 July bomb suspects came as a "surprise" to his sister, a court has been told.
Adel Yahya spent 2005 studying, his sister told the court
Lina Yahya told Woolwich Crown Court she had not heard of the book found at her brother Adel Yahya's London home.
The Secret World refers to "sacrifice in the cause of jihad, meaning people losing their lives", jurors heard.
Mr Yahya and five other men all deny conspiracy to murder and to cause explosions likely to endanger life.
About the book, his sister said: "This is a surprise. He's never really had these sort of views."
Asked if this meant Mr Yahya had never displayed any such views to her, she replied: "Yeah, never."
She also told court she was unaware that Mr Yahya had fraudulently received £532 from London Metropolitan University after pretending he had no money.
She had also not known that he had used a letter from the Immigration and Nationality Directorate, granting her indefinite leave to remain in Britain, to fake another letter.
Max Hill, prosecuting, said: "I'm suggesting, I'm afraid, that although Adel is your brother and although, no doubt, any sister would hope that she knows her brother well, there were things about Adel, particularly in 2005, which you knew nothing about."
She replied that during that year, he was studying, as she remembered him spending a lot of time in the library.
"I know him... He has passed his exams so I'm sure he must have been in the library studying."
The accused are Ramzi Mohammed, 25, of North Kensington, west London; Hussain Osman, 28, of no fixed address; Muktar Said Ibrahim, 29, from Stoke Newington, north London; Mr Omar, 26, from New Southgate, north London; Mr Yahya; and Manfo Kwaku Asiedu, 34, of no fixed address.
The case continues.