Who is Yero Lewis from The Glory Field and what is their importance?

Yero Lewis is the youngest of Moses and Saran Lewis' sons. Yero Lewis is born in 1857. The only mention of Yero in the narrative is made on page 87. Yero Lewis is named after his maternal great-grandfather. The narrator describes Yero as "a little touched in the head." Yero Lewis has a crippled left leg. Yero Lewis is Abby Lewis' father and Planter's grandfather.