Billie Eilish Wishes Brother Finneas Happy 26th Birthday: 'You Are the Best Thing I Have'

The ‘What Was I Made For?’ singer is celebrating her big brother Finneas on his 26th birthday

Billie Eilish is showing her love for big brother Finneas on his 26th birthday!

The 7-time Grammy-winner, 21, posted a throwback image of the pair on Instagram Monday showing Finneas looking at her adoringly as a newborn baby.

“My best friend forever. will never love anyone as much as i love you @finneas happy birthday you are the best thing i have,” Eilish, 21, captioned the image.

Related: Finneas Says He Has 'No Desire' to Be More Famous Than He Already Is: 'Seems Like a Huge Drag'

Eilish has often spoken about how crucial her big brother is to her music. Together, the siblings have released two No. 1 albums (When We All Fall Asleep, Where Do We Go? in 2019 and Happier Than Ever in 2021), won multiple Grammys and even taken home an Academy Award.

In July, Eilish revealed that she was going through a period of self-doubt that went far beyond writer's block before she and Finneas came up with their Barbie soundtrack contribution, "What I Was Made For?"

In an interview with Apple Music 1 host Zane Lowe, released on the same day as her self-directed music video for the song, Eilish said the song only came about when Finneas found the solution to their "frustration in writing."

Related: Billie Eilish and Finneas' Greatest Sibling Moments Together

"Finneas has always been the one that's like, 'No, no, no, let's write. Let's write.' And honestly, we were in a period of time where we were both ... like through this last winter, we've both been incredibly uninspired," Eilish explained. "And we've still been working and trying to make stuff. And honestly, that song was the first thing we'd written in a minute."

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Earlier this month Finneas also opened up about their life in the spotlight in an interview on iHeartRadio's Song Stories podcast shared exclusively with PEOPLE.

"Billie gets to play these arenas and whatever, but her day-to-day life is more challenging than mine," he told host Jordan Runtagh. "My ability to walk down the street and go into a grocery store and sit at a coffee shop and whatever is uninhibited. Maybe a kid or two that day comes up to me and goes, 'Hey, I love you,' or something, but it's not a challenge."

Related: Billie Eilish and Finneas' Greatest Sibling Moments Together

Related: Billie Eilish and Finneas Urge Fans to Stop Throwing Objects at Artists: 'Don't Do It'

Finneas added that he has no interest in achieving the same level of fame and recognition as his sister, and would "avoid it" if he could.

Despite this, he acknowledged that a certain level of notoriety is required for his music to hit as many ears as possible.

"The caveat is that I'm proud of my music. I want to promote it. I want it to be heard by as many people as possible. And if the consequence of that is that I become more famous, I'm willing to take that," he says. "I think a lot of people want to be famous, but I have no desire to be any more famous than I currently am. It seems like a huge drag."

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