Quote 40
But most important, hips are scientific, I say repeating what Alicia already told me. It's the bones that let you know which skeleton was a man's when it was a man and which a woman's. (20.7)
This "scientific" observation about hips suggests that gender is something you're born with. It's biological.
Quote 41
Everybody getting into it now except Nenny who is still humming not a girl, not a boy, just a little baby. She's like that. (20.27)
Nenny's nursery rhyme hints at the idea that gender is a social construction – it's not something you're born with, it's something you learn to perform.
Quote 42
And then Rafaela, who is still young but getting old from leaning out the window so much, gets locked indoors because her husband is afraid Rafaela will run away since she is too beautiful to look at. (31.1)
The issue of freedom and confinement becomes a gendered problem in this novel, as women are frequently confined to their homes by their husbands.