I think that all novels are somewhat biographical because if you give 10 authors the same prompt, each will create a unique story because we write from our experiences.
I'm sure Stephenie Meyer never interacted with vampires. But, maybe she felt ordinary like Bella. Maybe she was attracted to a young man that seemed perfect in every way while she was in high school. Maybe she feared for her family's safety at some point. Dave Farland spoke at the LDStorymakers Conference in April and he commented that Stephenie, a student of his at one time, wanted to write a story that included her core belief of chastity before marriage. She successfully did that when she created Edward who refused to give in to his desire because it wasn't proper in "his" time. Meyer used her experience to shape her story.
In my life, I lost my mother when I was a young girl, I lived in an anti-Mormon home, I interacted with non-members on a regular basis, I've had to resolve issues concerning forgiveness, I attended BYU and met my husband there, I met my future mother-in-law while dressed as a clown, my husband is from the country and I grew up in the city, and I was dumped by someone I thought I'd marry (though it wasn't at the altar). If you've read Heaven Scent or Altared Plans, you'll recognize these elements.
In my newest novel, The Upside of Down, which will be released in January, the main character is a mom raising a large family. I included many true-life experiences in this book, things my kids have done to me (embarrassing things). I've also included a storyline about Down syndrome, which is very close to me. My main character also has to deal with a demanding calling and an anti-Mormon mother, both of which I've experienced, though I've fictionalized them for the book.
Our experiences shape us as writers. When we write from the heart, we shed light on things in our own unique way. We see the world differently from our neighbor, even from our own family. It's in the way that we've experienced our lives that flavors our writing. My story is different from yours because I've lived a different life.
When we take our experiences and tweak them to fit our story, we give it a depth and a fullness that resonates with readers.