[Vocabulary] typical

I'm studying and reading "The Hostage" by Amelia Gray. I have one question. It's about a phrase from the book.

"You're the bitch who volunteered," he said.
"Wow," she said. "I guess I must have said something to deserve that."
She sounded exactly like his mother, which the bank robber realized was just typical.


My question is, what's the meaning of the underlined sentence?

She sounded exactly like his mother, which the bank robber realized was just typical
=
She sounded exactly like his mother and The bank robber realized that She was just typical woman. ???


what's the meaning of the underlined sentence?

I think that the writer is suggesting that the woman's sarcasm is similar to his mother's.

I think the writer might be suggesting that it is typical for any woman to sound (eventually!) like her mother.