Mary Shelley was the daughter of two famous radicals. Her mother, Mary Wollstonecraft, a writer and early pioneer for women's rights, died when Mary was quite young. Her father, William Godwin, was a famous writer and political philosopher. He was called "Jacobin" and "Guillotinist" for his hostility to the aristocracy and his approval of the French Revolution, at least initially. (The modern equivalent of these taunts would be "Communist" or "jihadist.") When Mary took up with Percy Bysshe Shelley, her father disapproved; Shelley was already married (His wife would later commit suicide, enabling Mary and Percy to wed in 1816) and he was a dreaded aristocrat. For all Godwin's disapproval of Shelley, he did not hesitate to ask him for money. In 1822, Percy died in a boating accident and Mary had to raise their son alone. The Courtney Love of her day, she was often accused of being an unfit mother.
Her father and husband made fatherhood a lower priority than their writing and politics. In the first edition of Frankenstein in 1818, she made Victor Frankenstein's father seem rather indulgent, but by the third edition in 1831, he was presented as feckless and distant. She portrayed Victor as someone who wrote passionate love letters to Elizabeth, but who spent all but a few days of his adult life avoiding her, in his lab and on his coaching tours. Victor's sole stab at fatherhood was to create a monster, without a woman's participation, whom he would spend the rest of his life trying to destroy.
Mary Shelley was a product of both the Gothic and Romantic movements, which (as stylistic elements) portrayed love as destructive and relationships as toxic. Her contentious relationships with her father and husband certainly contributed to this mix, but did not define it entirely.