No. No, no, no, no. You can't do this to us. No!

@TimeFrame No. There is no difference. Its just an aesthetic choice, not a plot-related choice.

@superkiller27 Multiple points there I think have been addressed (but not QUITE sure). As for the DeWitt dying in one universe then altering others, I believe Elizabeth established that while there are infinite universes (hence the title), there are events that are unique - that are the spawning point for all other universes. By that, it means that while there are infinite threads in every direction, every now and then, the threads head to a specific point that then spawns an infinite more threads from there. 'Smothering in the crib' was meant as stopping this one thread from ever spawning DeWitt or Comstock universes.

And yes, your point of going back and killing yourself contradiction is right on. But with most time-travel related things, the point is usually skipped. The argument, if you go back in time and kill your grandfather, could you do it, because then you would stop yourself being born and would not be able to kill your grandfather? Makes your head spin.

As for the Letuces, I believe that a voxophone states that Comstock's consistent presence in the Luteces work in quantam fields rendered him unable to have children. I believe that a universe with a DeWitt (with a kid) and not a Comstock was just chosen at random. Elizabeth's powers originated, as Lutece put it, from 'what she isn't, not what she is'. You could have taken any Elizabeth (or Anna), and the fact that she was brought in from a different would will still give her powers - it wouldn't have mattered which world.

I believe that is mostly right, but I am more than happy to be disproven.