Solving a mystery

So we had assumed that our house originally had a 2 car garage and that they took half of that garage and made it a part of the awesomely large kitchen. Last night, I crawled into the attic above the garage and found evidence otherwise:

That's an old exterior vent ----- this was the old outside of the home (there's one on the other side of the house too). So basically, what they did was took the one car garage, converted it into part of the kitchen. Then built a whole new garage and added it to the side of the house. 

Here's a bird's eye view ---- the pink boxes show the additions to the house:

The attic space above the garage was insulated with R-11 insulation (Energy Star recommends R-38 and higher is better). Bonus is that there was mostly plywood over that ---- so tons of Rubbermaid storage boxes of holiday decor could be relocated here!