Question: Garden of Shadows explains the origin of the grandmother from the first book in which V. C. Andrews series?

Context paragraphs:
Flowers in the Attic: Flowers in the Attic is a 1979 Gothic novel by V. C. Andrews.  It is the first book in the Dollanganger Series, and was followed by "Petals on the Wind", "If There Be Thorns", "Seeds of Yesterday", and "Garden of Shadows".  The novel is written in the first-person, from the point of view of Cathy Dollanganger.  It was twice adapted into films in 1987 and 2014.  The book was extremely popular, selling over forty million copies world-wide.

Frederic C. Rich: Frederic C. Rich is an American author, lawyer, and environmentalist.  He lives in New York City and New York State’s Hudson Valley.  Rich's first book, "Christian Nation", is a work of dystopian political fiction arising from the counterfactual of a McCain/Palin victory in 2008 followed soon after by John McCain's sudden death and Sarah Palin's ascension to the presidency.  It was published by W.W. Norton in 2013.  In "Getting to Green", a non-fiction book published by W. W. Norton in April 2016, Rich argues that the American environmental movement has lost its way and explains how it can get back on track.  The book calls for conservatives to reconnect with their long tradition of support for conservation and for the Green movement to adopt the reforms necessary to restore bipartisan support for the environmental agenda.

Heaven (Andrews novel): Heaven is the first book in the Casteel series by author V. C. Andrews.  It is also the name of the main character Heaven Casteel, in the Casteel series.

Grandmother Fish: Grandmother Fish: A Child's First Book of Evolution was written by Jonathan Tweet.  The book explains Charles Darwin's theory of common descent and its target audience is 3–5-year-olds.  It uses a call-and-response interaction between speaker and listener, where the child is asked to mimic the behavior of various animals from our evolutionary past.  The book is illustrated by Karen Lewis with colored artwork.  "Grandmother Fish" takes children and adults through the history of life on our planet and explains how we are connected.

Web of Dreams: Web of Dreams was written in 1990 by V. C. Andrews ghostwriter Andrew Neiderman.  It is the fifth and final novel in The Casteel Series, and serves as a prequel to "Heaven".  Told primarily from the viewpoint of Heaven Casteel's mother, Leigh VanVoreen, the novel explains her secrets and circumstances as a 13-year-old girl who was forced to flee her wealthy Boston home, resulting in her dying in childbirth and leaving her daughter Heaven to be raised motherless in the hills of the West Virginia mountains.

Garden of Shadows: Garden of Shadows is a novel by V. C. Andrews and was first published in 1987.  V. C. Andrews died in 1986, and her estate commissioned ghostwriter Andrew Neiderman to continue writing novels under her name developed from plot outlines originally written by Andrews.  There is some dispute over whether this particular novel was written in part by Andrews before she died, or whether it was written entirely by Neiderman.  This is the fifth novel of the Dollanganger series.  The novel explains the origin of Olivia Winfield (the grandmother from "Flowers in the Attic") and the events that cause her to become the cold, domineering mistress of Foxworth Hall and how Corinne's childhood and eventual betrayal come about.  The story takes place between the years of 1918-1957.

Midnight Whispers: Midnight Whispers is the fourth novel in the Cutler series, written in 1992 by the ghost-writer of V. C. Andrews novels, Andrew Neiderman.  The novel follows the traditional formula of Andrews novels, and by being the fourth in its series, it thereby centres on the child of the protagonist of the first three novels.

Chasing Shadows (EP): Chasing Shadows is the third EP by alternative rock band Angels & Airwaves, released on April 8, 2016, through To The Stars Records.  Similar to the "...Of Nightmares" EP, "Chasing Shadows" is a companion piece to the first book in the "Sekret Machines" series, co-written by Tom DeLonge and A. J. Hartley.  Along with the EP is a planned documentary series.

Luck in the Shadows: Luck in the Shadows is the first book in Lynn Flewelling's "Nightrunner" series.  Set in a fictional universe, the novel follows the adventures of a complex thief and his apprentice as they are targeted by magical forces and attempt to unravel a political conspiracy.  It is followed by "Stalking Darkness", "Traitor's Moon", "Shadows Return" and "The White Road".  "Luck in the Shadows" is being made into a movie.

Demon Thief: Demon Thief is a book in Darren Shan's "Demonata" series.  Though it is the second book in the series, it is a prequel to "Lord Loss", the first book in the series.  The protagonist is also different from that of the first book.  The narrator here is a new character called Kernel Fleck, as opposed to Grubbs Grady, the protagonist of the first book.  Demon Thief takes place about thirty years before "Lord Loss" so most of the characters from the first book did not appear, though a few did.  It was also actually the sixth book of the Demonata to be written, although it was the second released.

Supporting paragraphs: Garden of Shadows Flowers in the Attic
Answer: Dollanganger Series