Finneas would be "really sad" if he had no children before dying

He told the i newspaper: "If I only had six months to live, the only thing I'd be really sad about would be not getting to have kids.

"I'd say, 'Oh, that sucks.'

"Everything else, I'd be like, 'Man, I had such a lucky life.'"

While Finneas and Billie have a close relationship, both personally and professionally, he admitted it is difficult for them to go out together because the 'What Was I Made For?' hitmaker always attracts so much attention, they end up having to "run away".

He explained: "I'll plan out a thing for us to do.

"I'll be like, 'It's dark out, let's take the dogs on a walk.'

"And she's just so famous, man.

"We have to run away. It's crazy."

When he was 12, Finneas did a songwriting session with his mom, and it resulted in him joining his high school band, The Slightlys.

And in 2015, he wrote the song, 'Ocean Eyes', and he gave it to Billie because he felt she sang it better than him.

After uploading the end result to SoundCloud, the 23-year-old music icon became a household name, and Finneas said she knows her global fame is both a blessing and "a curse".

He said: "It's a gift and a curse that it's all she knows.

"She doesn't have that grief of suddenly not being able to go to a grocery store. She never did it.

"She does a pretty good job of having a self-sufficient life, all things considered."

And Billie previously revealed she and Finneas can "read each other's minds".

She told British Vogue: "I mean it's the sibling thing, you know?

"We look at each other in silence and we both know we're thinking the same exact thing.

It happens constantly, especially with other people around.

He can also read my mind when writing and creating together. He knows what I'm thinking and feeling before I even know it."