<P> In public , Joffrey is allegedly the oldest son and heir of King Robert Baratheon and Queen Cersei Lannister , both of whom entered into a political marriage alliance after Robert took the throne by force from the ' Mad King ' Aerys II Targaryen . In reality , his biological father is his mother 's twin brother , Jaime Lannister . He has a younger sister , Myrcella , and a younger brother , Tommen , both of whom are also products of Jaime and Cersei 's incestuous relationship . Their sole biological grandparents , Tywin and Joanna Lannister , were also first cousins . </P>
<P> In public , Joffrey is allegedly the oldest son and heir of King Robert Baratheon and Queen Cersei Lannister , both of whom entered into a political marriage alliance after Robert took the throne by force from the ' Mad King ' Aerys II Targaryen . In reality , his biological father is his mother 's twin brother , Jaime Lannister . He has a younger sister , Myrcella , and a younger brother , Tommen , both of whom are also products of Jaime and Cersei 's incestuous relationship . Their sole biological grandparents , Tywin and Joanna Lannister , were also first cousins . </P>
game of thrones who is joffrey 's father
game of thrones who is joffrey 's father
his mother 's twin brother , Jaime Lannister
his mother 's twin brother , Jaime Lannister