So he had seen her parents. Aerith has precious few memories of her mother and none of her father, which she sees as a blessing. She had been a newborn when Gast was killed for betraying Hojo (and thus Shinra).

"The worst monster of them all experimented on you, too." yes, she makes a distinction there by adding 'too'. Hojo had experimented on her and her mother - until the latter was too sick to keep living.

"Don't give her too much credit." she cautions, "You would be strong and a leader without her in your blood."

As for absolution... No. That doesn't belong to any of them.

"You contradict yourself." her green eyes seek his gaze, "The weight of her will - the burden of it - would have just been the beginning. If you stood against her, she could have driven you completely insane and turned you into nothing more than a mindless puppet. You chose to retain what sanity you could and that's why you feel guilty."