How do Cersei and Jaime know Joffrey and Tommen are theirs?

Okay. To thoroughly understand this, one must also be into the books. The show makes just one reference to how Cersie was definitely sure that all her three children were from Jamie. read more

And while Cersei focused on Joffrey she completely ignored Tommen and Myrcella. However it’s possible that if she focused on them as well they would grow up to be the same psychopaths as Joffrey. So it’s perhaps better that she ignored them. read more

All Robert's children, not from Cersei were dark colored just like him. And many of them looked like him. All Jon Arryn and Ned Stark had to do was take one look at Robert Baratheon's children by Cersei, and know that none of them were his. read more