What is symbolic about Jean de Satigny's perversion and why does Allende include it?

Initially, Blanca is quite happy in her marriage to Jean. But, as she discovers some rather unpleasant facts about his sexual predilections, she sees a totally different side to him. The precise nature of Jean's sexual perversions is never quite established. At the very least, though, he seems to have some kind of fetish for using indigenous men and getting them to pose for erotic photographs. On top of this, Blanca discovers Jean's drug abuse as well as his shady business practices.
The House Of The Spirits incorporates numerous examples of what is called magic realism. This is a literary style that uses elements of fairy tales, fables, and folktales to heighten the sense of realism being presented. And Allende uses this method in relation to Jean's sexual perversions. In doing this, she is engaging in social commentary on contemporary Latin America: Allende wants to highlight the serious plight of Latin America's indigenous populations. Their sexual exploitation at the hands of Jean is symbolic of their wider treatment in society.
Magic realism is an effective means of dealing with age-old themes in a way that is both imaginative and relevant to the present day. Dealing with social and political themes using traditional realism can often lead to their becoming quickly dated. However, Allende's use of magic realism allows her to tap into a deeper structure of meaning, one reflected in countless myths, fables, and stories that never truly age and whose important themes resonate through the ages.