Shane and Shawn Green have always been inseparable.

The identical twins played Little League together. They shared a dorm room in college, where they were both guards on the basketball team.

And in their 20s, when they moved into a buddy’s house in west suburban Berwyn, they kept their bedroom doors open so they could talk to each other before drifting off to sleep at night.

“We’ve always done everything together our whole lives,” said Shane Green, 41, who lives with his wife and two daughters in Homer Glen.

But the twins know that perhaps a time is coming soon when that won’t be the case. Shawn, who is married with a 3-year-old daughter and lives in Roscoe Village, has inoperable brain cancer.

So on Sunday, Shane and Shawn took part in the Chicago Half Marathon — something they’ve done together for four of the past five years. Shane pushed Shawn for 13.1 miles in what was, essentially, an adult-sized stroller. Their families and friends gathered as Shane helped Shawn to his feet, and the brothers walked across the finish line. They embraced for several seconds afterward, recognizing it could be their last race together.

“It was actually one of the easier runs I’ve ever had, I think it’s probably just being inspired to push him and get to that finish line,” Shane said.

Shane and Shawn’s run was reminiscent of the father-son team of Dick and Rick Hoyt, who was born with cerebral palsy. The duo completed more than 1,000 races, including the Boston Marathon and Ironman competitions, with Dick pushing Rick in a specially designed wheelchair.

The twins were born and raised in Bernie, Missouri, a small town in the southeastern corner of the state.

“He’s about an inch taller, but I’m a minute older,” Shane quipped last week.

From a young age, they embraced their rare circumstance.

“We had the same hair, same taste in everything, same sports — except women,” Shane said.

Twins Shane and Shawn Green were on the basketball team in high school, then chose to attend the college that would accept both of them, so they could keep playing together. | Provided photo

Twins Shane and Shawn Green were on the basketball team in high school, then chose to attend the college that would accept both of them, so they could keep playing together. | Provided photo

They each had offers to play basketball in college. They chose the college that would accept them both — the University of St. Francis in Joliet. When they got married, they were, naturally, each other’s best man. They both got jobs in the Chicago area.

So when Shawn was diagnosed with a brain tumor in 2009, it only made sense that Shane would be at his twin’s side through it all. Shawn had surgery to remove the tumor that same year, but it returned, more aggressively, in 2015.

“We’re concerned, in that the tumor has transformed, but we remain optimistic that one of these novel medical treatments will potentially slow it down, if not cure it,” said Dr. James Chandler, surgical director of neuro-oncology at Northwestern Memorial Hospital.

Last week, Shane accompanied his brother — and Shawn’s wife, Erin — to an appointment at Northwestern. Shane slipped a hand under his brother’s elbow to help support him. The tumor has robbed Shawn of much of his ability to speak and the use of the right side of his body. He walks with a cane now. Shawn’s now-frail frame could fit comfortably within the outline of his brother’s.

When Shawn went into the changing room to prepare for the CAT scan, Shane accompanied him.

“It’s like you get one with the other,” said Erin Green. “They come as a pair. It’s a very special relationship. It’s something I know Shawn cherishes. He loves Shane unconditionally.”

At lunch that same day, while Shane talked about their relationship, Shawn sat nearby.

Twins Shane and Shawn Green. | Provided photo

Twins Shane and Shawn Green. | Provided photo

“I asked him a couple of weeks ago if he wanted to run [the half marathon] with me,” Shane said. “I wanted to cross the finish line with him again. So that’s what we’re going to do.”

As Shane spoke, Shawn swiveled his head down and away to hide welling tears.

In another conversation, Shane was asked about the possibility of life without his twin. No one can predict, he said, how a person will cope with death.

“To look into a person’s eyes and see defeat is tough, especially when it’s your twin brother, who is everything to you,” Shane said. “There is a void that will never be filled when he is gone.”

In the meantime, the twins — and their families — subscribe to the motto: “Every day is a good day.”

The twins have the words tattooed on their torsos. A month ago, Shane got another tattoo — two “S’s” side by side in the center of a shield.

“It’s me protecting him,” Shane said. “It means something to me. It will forever be with me.”

Twins Shane and Shawn Green grew up in Missouri. | Provided photo

Twins Shane and Shawn Green grew up in Missouri. | Provided photo