Does the conversation with Matriarch Aethyta go the same way if you haven't watched the video archives in the Shadow Broker base?
Solution 1:
According to the Mass Effect Wiki entry for Matriarch Aethyta you merely need to complete the DLC for Shepard to mention this.
If the player has completed Lair of the Shadow Broker, Shepard will directly mention the vid of Aethyta looking at the picture of Liara
My experience with this scene is that I do not even own the Broker DLC. Importing that Shepard with this convo did not even mention the video, but she still revealed herself to be Liara's father, with Shepard having...an awkward time accepting a female as a 'father'.