Who was raped at the age of eight?

Near the beginning of The Brief and Wonderous Life of Oscar Wao, it is mentioned that Oscar's sister, Lola was raped by a neighbor when she was eight years old. Interestingly, this is said by the narrator in a very casual way. So casual in fact that one can almost miss it in the reading. It is unclear exactly what the neighbor did, but through context, we can assume that young Lola was sexually assaulted, and likely raped.
There is a strange, yet poignant, hushing up of sexual assault throughout the novel. In Chapter 3, it is alluded to that Belli, Lola's mother might even have been raped while a young woman in the Dominican Republic. It is unclear if this is what happened, but the reader is left wondering.
When Lola mentions what happened with the neighbor to her mother, she is told to never speak of the matter.

When that thing happened to me when I was eight and I finally told her what he had done, she told me to shut my mouth and stop crying, and I did exactly that, I shut my mouth and clenched my legs, and my mind, and within a year I couldn’t have told you what that neighbor looked like, or even his name.

This theme of shame around sexual assault remains a dark undercurrent throughout the narrative.
Interestingly, author Junot Diaz recently published an essay about his own childhood rape (which happened at age eight) and the silence he kept about it throughout his entire life up until now. In the essay, he mentions how this defining experience both subconsciously and consciously influenced his writing.
https://www.newyorker.com/magazine/2018/04/16/the-silence-the-legacy-of-childhood-trauma