Kitty Kelley takes the following

As a politician, Prescott [Bush] grew in office. In his first campaign he stood up to the rampaging redbaiter Joe McCarthy — an act of political courage in 1952. As a United States senator, Prescott championed civil rights, whereas his son George Herbert Walker Bush called Martin Luther King ”a militant” and opposed the Civil Rights Act. George W. hung a Confederate flag on his wall at Andover, joined a ”whites only” club in Texas and as president refused to address the NAACP. Bush 41 and Bush 43 have far surpassed Prescott politically, but both presidents look like pygmies compared with the patriarch.

I haven’t read Kelley’s book and don’t know about the other allegations in this paragraph, but the NAACP claim is a red herring. Bush didn’t speak to the group because NAACP chairman Julian Bond has made all sorts of hateful and derogatory comments about him and the Republican Party, including claiming that Bush’s Cabinet nominees come from the “Taliban wing” of American politics. As a result, Bush has generally chosen to address other African American groups like the Urban League instead. This is hardly de facto proof of racism or being anti-civil rights.