Family Drama; Fantasy; Horror or Gothic Fiction
It's pretty easy to see why Dandelion Wine should be classified as a family drama—you'd have drama, too, if your parents lived next door to your grandparents and they all ran a boarding house together. Back in 1928, families tended to stick together more than they do now. People weren't as mobile; they didn't just find a new job on Craigslist, book a cheap one-way ticket on Priceline, and go off to start a new life.
Remember: Miss Fern and Miss Roberta are willing to pay ten bucks a month (which is a whole lot more in today's dollars) for a vehicle that maxes out at fifteen miles per hour. In short, no one's going anywhere fast. And with so much family in the mix, enough of this plot is driven by interactions between family members that it lands in the family drama genre.
And then, of course, there's a serial killer on the loose in Dandelion Wine, too. And while Miss Fern and Miss Roberta's vehicle payment might seem terrifying, dead bodies with bulging eyes and lolling tongues are way more horrifying. So there's definitely a feeling of dread in this book, which means it also hangs out in the horror/gothic fiction arena.
As for fantasy, well, Mr. Auffmann builds a virtual reality device in the garage out of scrap metal and orange paint, Mr. Jonas bottles magical healing air potions, and Clara Goodwater wins the presidency of the Honeysuckle Ladies' Lodge with voodoo. Enough said.