There are three important women in the novel: La Inca, Beli, and Lola. Each are strong women who battle each other, men, the fuku, their past, their color, and--most importantly--stereotypes (or archetypes). Each one is associated with an archetypal attribute and geographical location: La Inca (the DR); Beli (the DR & US); and Lola (the US). All are foils of each other and, most importantly, Oscar. With each woman that we meet (and we meet them in reverse chronological order), we think each one is the originator of the fuku. Each one, then, is a kind of red herring or scapegoat.
The key chapters are 2 & 3: "Wildwood" as narrated by Lola (1982-1985) and "The Three Heartbreaks of Belicia Cabral" about, not narrated by Hypatia "Belicia" Cabral (1955-1962). Notice that only Lola has a narration. We must assume that since Yunior, the primary/outside narrator, dated Lola, he has imbedded her narration within the novel as a primary source. He has no such relationship with Beli, of course, so he only tells of her story second-hand. This makes him a somewhat biased and unreliable narrator. What's left out, of course, are Beli and La Inca's narrations.
Each of the three women is a kind of comic book or archetypal hero whose attributes are exaggerated for comic effect. For La Inca it is her spirituality, for Lola it is her butt, and for Beli it is her breasts. Since we have an oversexed narrator in Yunior, he may be stereotyping the women as saints or sinners for effect, but since most men from the DR characterize women this way, especially Trujillo, we must see these women as they do. Of the three, Beli (short for bellicose: "warlike") is the villain, the darkest skinned, the one most affected with the curse, the one in closest contact with Trujillo, the one who brings the curse to the U.S. The focus of the novel, then, is to determine if Lola will turn out like her mother, or be saved. Oscar, our hero, preempts and determines Lola's fate.
In Chapter 3, there's a key passage in the book that suggests that Beli wills her big breasts upon herself, as a supernatural attribute to attract Jack (who had ignored her up until then). It's a very short section within the chapter, but the subheading is "Kimota." According to annotatedoscar.com:
This is what Micky Moran says to transform into Marvelman (phonetically, "atomic" backwards)
This is when tragedy begins for her (so we think). She moves from a strong-willed character to a weak one. With some homespun magic, Beli is bringing the fuku upon herself. Her breasts, in effect, seal her fate. Their overdevelopment makes her a plaything for men. She makes a pact with Trujillo, the dark lord. She feels she is fated to sabotage herself because of the prevailing sexist gender roles and color codes (that condemn her as evil because she is so black).
La Inca is the matriarch of the family. She is, according to Jungian/archetypal criticism, the Earth Mother/Goddess or Spirit/Intellect guiding force, much like Ursula in 100 Years of Solitude. She maintains the social and historical. As Enotes editors say:
La Inca is also a religious woman who strongly believes in the power of prayer. She counts on these beliefs to heal those around her. She tries to instill moral strength in Beli and in Oscar, wanting them to use the intelligence that they inherited from her brother (Beli’s father).
The other two are essentially doppelgangers of each other. Of all three, Diaz (or Yunior) vests most of his energies in Lola, I think, because she touches Oscar the most. She runs far away (to Spain) to escape the curse. She is the survivor that Beli is not. As the Enotes says:
Lola, in many ways, is a combination of her mother and her aunt La Inca.
Lola does survive the curse, of course, thanks to Oscar's redemptive sacrifice.