Emelina's five sons are pretty delightful. We only get a few short glimpses of their lives, but we know that they all dig their Aunt Codi.
John Tucker is the oldest. We know because he has his very own goat. He likes watching MTV and hanging out in the bushes while his brothers go trick or treating and looking sulky. Glen and Curtis like trying to act grown up, eating candy and messing around with the marigolds on the Day of the Dead. Mason is rarely seen in the narrative, but he's clearly a speed demon on the tricycle, and Nicholas is the baby of the family. He's the one Codi saves from death by refried bean, and Codi also watches him learn to walk by following a hummingbird in the garden.
Overall, they seem like awesome kids. Their main purpose in the story, though, is to show how great with children both Emelina and Codi are.
One interesting thing about these kids, however, is their names. Note that Emelina and Juan Teobaldo both have Spanish-derived names. John Tucker is named after his dad J.T., but the initials stand for names that are far more Anglo. In fact, Kingsolver makes a point of noting that J.T.'s accent is much less Spanish-influenced than the accents of his elders. He pronounces the word quince as "quince," for example, rather than "queenz" like the old guys in town. Emelina says her parents were pretty Americanized (they almost named her Gidget), so it's not all that surprising that she gave her kids Anglo names.
Even so, through the fact that these boys have names like Mason and Glen, Kingsolver seems to be pointing to slow and subtle changes in Grace's culture. Maybe the town is not as hermetically sealed off from the rest of America as Codi thinks it is.