 When Dr. Taylor Hayes, Thomas' mother, discovered the pregnancy, she attempted to tell Ridge Forrester (his father) in a joyous mood.However once she saw him being seduced by Brooke Logan once again she nearly lost the baby due to stress.So that Ridge could be happy with Brooke, Taylor told everyone (and Brooke was in on this lie as well) that Thorne Forrester, Ridge's brother, was the father.