had not taught my father to drive at the age of twenty (14)
There's the old man! Our speaker begins to relate all of this family business to his own. It's getting slightly more personal.
in Pittsburgh where my mother was working and if (16)
And here's mom. We see where this is going!
my mother had not lost both her parents when she was a child (17)
We thought we were moving forward to the speaker's birth, but here we take a mini-step back to his mom's family, before she officially meets our speaker's dad.