Lori and George Schappell, the oldest conjoined twins in the world, have died at the age of 62.

The siblings died Sunday from undisclosed causes at the Hospital of the University of Pennsylvania, according to a joint obituary published by Leibensperger Funeral Homes in Hamburg, Pennsylvania.

They were born in Pennsylvania on Sept. 18, 1961, with their skulls partially fused and shared vital blood vessels and 30% of their brains, Guinness World Records said about the record-setting pair.

Lori and George became the world’s first conjoined twins to identify as different genders in 2007 when George transitioned to a man.

They were also nine years older than the second-oldest female conjoined twins ever, according to Guinness.

Lori Schappell and George Schappell,
Lori and George Schappell died Sunday at the age of 62.FilmMagic

Their condition is the rarest form of conjoined twinning, representing only 2-6% of cases.

Lori Schappell and George Schappell,
Lori and George Schappell were born with their skulls fused together.FilmMagic
Despite spending every living moment together, the two had very different interests and careers.

“It was very important for Lori and Dori to live as independently as possible,” their obituary states. “Since the age of 24, they have maintained their own residence and have traveled extensively.”

Lori was able to walk while George, who was four inches shorter and diagnosed with spina bifida, got around in a wheelchair Lori pushed around, according to a 2002 Los Angeles Times report.

They each had separate rooms in their Pennsylvania apartment, and split spending nights in each one. They showered at different times and had different hobbies.

George performed across the world as a country music singer and Lori was an award-winning bowler. Throughout the 90s, Lori also worked at a hospital laundromat when George wasn’t touring.

Lori Schappell
Lori SchappellLeibensperger Funeral Home

George Schappell
George SchappellLeibensperger Funeral Home

They appeared in numerous documentaries and even made a guest appearance on the hit medical drama “Nip/Tuck” playing a fictional pair of conjoined twins.

Surgery to separate the two at birth was not available when they were born and they weren’t expected to live past the age of 30.

After they were born, they spent the first 24 years of their lives living in a mental institution after their “frightened and confused” parents placed them there, they told New York Magazine in 2005.

But they never expressed any desire to be apart from one another. Throughout their lives, despite their attachment, they were never actually able to look at each other.

“I don’t believe in separation,” Lori told The Times.

“I think you are messing with God’s work.”

“Would we be separated? Absolutely not. My theory is: why fix what is not broken?” George similarly said in a 1997 documentary.

They are survived by their father, six siblings, several nieces and nephews, and an extended family of friends, according to the obituary.