Harley Quinn Question

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I am currently reading Harley Quinn #9 Nerd Rage with your Birdcage.

She alludes to two different origins in this issue. One is Batman's. Who does the other backstory refer to?

Thanks for your help!

Picture is blurred. The quote is as follows:

"Tell me, did ja grow up without a father an' have two older sisters... an' did the sisters run away from home at an early age 'cause your mother was abusive...an' your mother died a' natural causes then left the house to you?"