Quote 7
"Gemma, Mother's murder is a blight on this family. It would be scandalous if the true facts were known." He stares at me. "Mother died of cholera," he says emphatically, as if even he believes the lie now. (3.47)
Tom is trying desperately to keep the family out of gossip, to make sure they stay in good standing in society—it ensures he and Gemma will both be able to marry into a lot of money. Funny how Gemma doesn't care about this though, and instead wants nothing to do with the lie.
Quote 8
"Ann, darling," I say, copying Pippa's chummy tone from earlier. Everyone seems surprised to hear me speak, no one more surprised than I am at the moment. "Don't be modest. Tell Miss Moore the truth." […]
"The t-t-truth?"
"Yes," I say, hoping I can make this up as I go along.
"The truth—"… (6.54-57)
Oh no she didn't… Gemma comes back with an awesome lie to rival the Torture Twins. We don't feel bad at all about it either because she does it to get poor Ann out of hot water.
Quote 9
"What if I just used a bit of magic, just enough to help Father and my friends with it—nothing else?"
She takes me by the shoulders like a child. "Gemma, you must listen to me. Do not take the magic out of the realms. Promise me."
"Yes, fine!" I say, tearing out of her grasp. (25.92-94)
This isn't a lie yet, and it doesn't become one until later on when Gemma breaks her promise and betrays her mother—but we think Gemma shows that she isn't serious about her promise here, and chooses to lie to her mother to get her to stop. Classic teen move.