People were saying that DX3's intro is derivative of IW's, and I really don't see the connection. In DX1 you're a new recruit to UNACTO and the second Nanotech soldier. In IW you're yet another nanotech person, and currently a student in "Tarsus Academy", being trained to serve the WTO. In DX3, you're an average guy security guard who through a series of events ends up getting the Robocop treatment as far as I know.
Edit: HP, Paul is 11 years older than JC. JC in DX1 is early to mid 20's, so he's either a newborn or a fetus in a test tube (omg tie-in to the DX3 debut trailer!) circa this game.