• Any secret is great for storytelling. One of the fundamental elements that stories need is conflict, and secrets provide that in shed-loads. Whether the protagonist is trying to cover up a secret or uncover one, different interests are being pitted against each other and the reader will want to know which side wins.
  • Secrets are key to the pacing of your narrative. Most of the time the reveal will only happen at the end of a novel; if you keep the secret in the foreground up to that point it builds tension and momentum, and the reader will be hooked.
  • Family secrets are even better than most because they touch on our sense of self. For the most part, your family are the people you've spent most time with, and the people you (think you) know best. We assume roles within a family, and look for similarities between one another; finding out something unexpected about a member within that unit can lead to doubts about our own identity, and a protagonist questioning their identity makes for great dramatic tension.
  • Families can be combustion chambers: rivalries, allegiances, insecurities can lead to multiple secrets being kept from multiple players in the family unit.
  • Writers can go 'all out' when a family secret is revealed, or even in the lead-up - keeping the secret can have consequences too. Often we feel more comfortable saying things to our family we wouldn't to friends; arguments are no exception, and...
  • ...this can sometimes lead to more dramatic outcomes, such as an estrangement between one family member and the rest. This also adds pathos - there's something about not having anyone who understands exactly what his or her life was like as s/he was growing up that really isolates a character.
  • Readers often like to feel that they're seeing and understanding more than the characters do (dramatic irony), but at the same time they like to be surprised. Secrets are a way to achieve both; readers can be fed enough clues that they know a big reveal is coming, even if the character doesn't, but they wouldn't necessarily be able to guess the secret exactly.
  • People react differently to having to keep in secrets. Some people feel guilty; some people are nervous; some people enjoy knowing something others don't. Whatever they feel, it's a great way to explore a character and some powerful emotions.
  • Often, as we grow up we become more curious about older family members because we start wanting to put our own experiences and personalities in context. It's hard enough coming to terms with the idea that your grandparents had lives before they were grandparents; throwing a secret into the mix can make it even more disconcerting.
  • Ultimately, we hope that families will be more forgiving of one another's secrets. It's comforting to have a move towards reconciliation by the end of a novel, a relief after the steady increase in tension readers may have felt as the moment of the reveal drew closer.