It's certainly not uncommon to refer to your best pal as a brother.
While they may not be blood-related, the support they have provided you over the years sees them classified in that family category.
Alan Robinson and Walter Macfarlane met in sixth grade and quickly became best mates.
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Growing up in Honolulu, Hawaii, the pair played high-school football together.
Their strong bond continued after they fished education, to the point where they were Uncle Walter and Uncle Alan to each other’s kids, as per Reader's Digest.
Both of them had one very strong similarity: they were both put up for adoption when they were younger and had no idea about parts of their biological family.
Walter, a retired math and physical education teacher, knew that he had a complicated family tree.
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His mother had been young when she had him during World War II, and it was concluded that she couldn't raise him on his own.
So, the family decided that his grandmother was to act as his mother and his biological mother was his sister.
Walter didn’t learn the truth until he graduated from high school, though he remained clueless about his father.
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In 2016, Walter’s daughter, Cindy Macfarlane-Flores, suggested her father try a DNA-testing kit.
Cindy noticed a user named Robby737 and that her dad shared enough DNA to be half siblings after using Ancestry.com.
Well, that rang a bell to many, as Alan's nickname was Robby, and he used to fly 737s for Aloha Airlines.
Surely not?
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Well, you can see where this story is heading.
The two friends then spoke on the phone, with Alan confirming he was Robby737.
Walter and Alan remarkably discovered they shared the same birth mother after an extraordinary phone call.
"It was a shock," Walter told KHON2.
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"Yeah it was shock, definitely and then we thought about it and compared forearms," Alan added.
He continued: "It was an overwhelming experience, it's still overwhelming. I don't know how long it's going to take for me to get over this feeling."
To add to the extra special feeling, the pair discovered their news during the Holiday season.
"This is the best Christmas present I could ever imagine having," Alan said.
While Cindy, who arguably played the biggest role in helping the pair discover they are brothers, quipped: "It really is a Christmas miracle, and we're just so happy that we found it."
Callum Jones