Novelist Lian Dolan is quick to say she has long been a professional sister but was loath to write about sisters.

As the youngest of five sisters, she knows a lot about being a sister and how birth order can affect one’s sense of self and identity. She and her sisters created a widely popular radio show and later podcast, Satellite Sisters, that launched in 2000 and now is syndicated.

Sisterhood does figure prominently in her newest book, “The Sweeney Sisters,” which will be available on April 28, even though the sisters in the book are not based on her own. “I have been immersed in sisterhood for a long time but it’s taken me a long time to write a book about it because I didn’t want people to think I was writing about my sisters,” she said. “These are fresh fictional characters but I know that people are really interested in how sisters interact behind the scenes.”

Growing up in Southport, a tiny hamlet of Fairfield, Conn., along the Long Island Sound, Dolan spent what can perhaps be described as a picture-perfect childhood. While Pomona College in Claremont, Calif., brought her out to the West Coast, where she still lives (Pasadena is now home), she retains a fondness for Southport so it was a no-brainer to set her book there, the first time she has done so, however. Her previous books,” Helen of Pasadena” and “Elizabeth the First Wife,” were set in California.

The book, which Good Reads recently just named as one of its most anticipated books for April, centers on three sisters, who grew up happy in Southport but drifted apart after losing their mom to cancer. Fifteen years later, when they hold a traditional Irish wake for their father, they discover a fourth sister, thanks to DNA testing, changing family relationships and raising many questions. Secrets and scandals dominate the plot but the overarching theme is of sisterhood and what it means to be —and have — a sister.

The Satellite Sisters podcast and its Facebook group draws many fans and it was actually a Facebook post by a follower that inspired this book. The person had posted a picture of her and her sibling meeting for the first time a newly-found brother, discovered through DNA testing, with the caption, “Isn’t it great?” This got the author wondering if that actually would be great. “People are learning ‘Mom did something 30 years ago or Dad did something 50 years ago and I have this half sibling’ so it was a good jumping-off point for a story.”

While this book is fiction, it is something a growing number of families have had to deal with, changing family relationships and forcing children to come to terms and accepting their parents as people with flaws. The characters are fictional but Dolan did say, out of all the sisters in the book, she most identifies with the youngest sister in the book, Tricia. “I’m the youngest of five sisters and the youngest of eight kids so I’m always going to stick up for the youngest,” she said. While Tricia and Dolan share some qualities, they are not the same. “She’s a lot more disciplined than me. She went to Yale Law School, I couldn’t have gotten in. She’s a runner and that’s not something I’ve ever done but there are certainly take-charge parts of her character that I relate to,” Dolan said.

“For years on our podcast and in all of our Satellite Sisters’ written work, I’ve been the executive producer of the show so I have determined the creative direction of the show and sometimes that shocks and annoys my older sisters but that’s kind of my role in the family,” she said. “I relate to Tricia just because I like to stand up for younger siblings. I think a lot of time in books, in any kind of creative medium like TV shows and movies, they are sort of babied and they are not very mature and it was kind of the opposite in our family. I was just left to kind of fend for myself and as a result I think I have a pretty strong sense of self.”

Using Southport for the setting allowed Dolan the joys of reliving her childhood and reconnecting with many friends and people still living there as she did research on what the town is like now. “I took it really seriously, I wanted to get the details right, I didn’t want it to be a book of memories, — although I had really strong memories — I think of Southport as just being this perfect place to grow up,” she said. “I had a lot of inside information and so it was fun just to go back and take photos of places I was going to use and change them in the way you can do in fiction but make it real for people who still live there.” The father character, Bill Sweeney, is a literary lion and college professor who was based on real-life author Robert Ludlum, who lived in the next town over, Westport.

“I hope the book is seen as a warm celebration of what a special part of the world that is. I think that there is just a wonderful heritage there and tradition and I miss it,” she said. “In the book, to me, in particular, the Fourth of July scenes are a bit of a love letter to the town.”

For more information about Dolan and her book, visit liandolan.com.