Lily and Madeleine’s mum might be flying to England with her silky-voiced daughters but she’s definitely no “momager”.

“They are stage parents,” explains Madeleine, “the parents of kids who get into the entertainment industry because they’ve been pushed hard.”

Madeleine, 19, dropped out of her college course but intends to return next year. Lily, 17, is doing online classes to cover this year’s high school second semester.

Given their ages and situations, outsiders might think they’ve a momager directing their career.

“She is definitely not a momager and we are grateful for that,” adds Lily. “She is supportive without being suffocating.”

The duo are speaking from Indianapolis, the capital of Indiana and home to the Indy 500 speedway. Madeleine recently moved back there to make music with Lily.

“It’s weird to be back after having a bit of freedom,” admits the elder sibling. “It can feel suffocating but it is definitely my choice.”

The two girls have sung together since they were young but only began to write as a partnership a couple of years ago.

They often sing three-part harmonies with their mother for fun and she has performed with the girls before. They might one day ask her to be on a record.

“We will suggest that to her but I think she probably wouldn’t want to. She wants to let us do our own thing.”

The sisters, who both play piano and guitar, tour without a band, which is perhaps why mum is coming on tour rather than to make sure they’re behaving themselves.

“She doesn’t have to worry about that. We are well behaved.”

It fits the wholesome image of siblings with choir-girl voices from a musical family in the Midwest. It creeps into your mind as you listen to their tales of innocence and curiosity delivered with subtle harmonies only blood relations could weave.

But it is their hometown, birthplace of 1980s heartland rock and folk pop crossover John Mellencamp, which Madeleine says is among the biggest influences on the 12 tracks penned with Kenny Childers of Gentleman Caller and released on the label Asthmatic Kitty co-founded by Sufjan Stephens.

“Growing up in Indianapolis definitely influenced our music. A lot of the nature imagery on the EP was influenced by the area we live in because it’s really beautiful and we’ve lived here all our lives.”

The idea that they might be twee horrifies, adds Madeleine, as we talk on speakerphone.

“We don’t want to be seen as the cute little sisters from Indianapolis who do folk stuff all the time.

“Even though that is a great image and great music comes from that. We just want to see what we can do. We have time and we are just starting out so why not experiment a little bit?”

Madeleine says the follow-up to their recently released eponymous debut record will see them experiment They’re big fans of Lorde – “super cool and interesting” – and love Arcade Fire and Lana Del Ray.

The debut record has something approaching the craft of Fleet Foxes mixed with the vulnerability of First Aid Kit.

Co-writer Childers helped the girls bash their lyrical ideas and melodies into songs, but Madeleine admits the harmonies needed no work whatsoever.

“The harmonies we write are really natural. We pretty much never have to think about it, which is the cool thing about being sisters.

“We can follow each other so I know if Lily starts a lower melody part, I can do high harmony and she won’t be fazed by it, she will just follow me along.

“We do that on all our songs. It’s one of my favourite parts of writing, adding those harmonies, making the melodies more dynamic and interesting.”

  • Lily And Madeleine play Sticky Mike’s Frog Bar, Middle Street, Brighton, on Saturday, February 15. Doors 8pm, tickets £8. Call 01273 749465