By excluding the backstory, David Gordon Green also reinforced the fact that Halloween is really Laurie’s story — what matters most isn’t how she became a mom, but that she rises to the occasion when her family needs her the most.
Okay, so maybe that’s a little anticlimactic.
It makes sense why that detail wasn’t included in the final cut, though – it’s kind-of hard to squeeze a story about a drunken one-night stand in the middle of a bloodbath.