How do Polly and her brother get along in the novel, A House Like a Lotus?

Xan is Polly's teenage brother, and his relationship with Polly is, at times, strained. He and Kate, Polly and Xan's cousin, bring up the question of Max's sexual orientation over dinner one night, suggesting that perhaps Polly ought not spend so much time at Beau Allaire, as her presence there is inciting gossip at the high school. Xan is severely chastised by Mr. O'Keefe and later admits his wrongdoing and apologizes to Polly.