In the Disney movie "The Hunchback of Notre Dame", Frollo takes for granted the gyspy woman that tries to save baby Quasimodo is his mom. But I've found a pair of details that actually point out that Quasimodo and the gyspy woman aren't related: 1. Quasimodo doesn't have the hair and skin color of a gyspy. 2. Neither she or the gyspy man with her call Quasimodo "son" (they may not be wife and husband!).
In the novel, Quasimodo's origin is unknown: He was left abandoned on the street, then he was found and adopted by Frollo because of compassion. Later in the novel, Frollo turns evil and insane because of his lust towards Esmeralda. Based on this, it is interesting to notice that Disney split the novel's Frollo into three characters: Frollo himself, the Arch Deacon and the gypsy woman, so it can be concluded that she adopted Quasimodo because of compassion.