The House of the Spirits is a family saga, so it's pretty much impossible to avoid talking about the theme of family in this novel. The text examines relationships between mothers and daughters, fathers and children, brothers and sisters – you name it. And it also looks at how families function as a whole unit – not always smoothly, it turns out, but there's something that keeps them all together. That mysterious glue might be a legal bond (like marriage), biological inheritance, physical intimacy, co-habitation, or just plain old love. Often it's some combination of those things. Our point is that it's not always easy to tell what makes two people "family," but the bond sure isn't easy to ignore.
The extended family portrayed in The House of the Spirits serves as a microcosm of society as a whole. We can think of the Trueba-del Valle family as a tiny society whose trials and conflicts mirror those of the greater society in which they live.
The traditional notion of patriarchy is constantly undermined in The House of the Spirits, and is replaced by a strong matriarchal connection among the women of the family.