User blog:Horselover&rider&owner/Why did Uther lie about Morgana?

I know this may be old in earlier seasons and you might be bored reading it, but I just want to know...

Why didn't Uther tell the truth about Morgana being his daughter?? Perhaps I haven't been paying attention to that episode or my memory has just faded away, but whatever it is, I would like to know why he didn't tell the truth about Morgana being his daughter and not heiring her as rightful princess to the throne?

Sorry, old type of topic I know, but I've been wondering this for a long time.