Kardashian Family Photo: Mystery Guy Identified ... I'm with Kanye!

Everyone chill ... the Kardashian/Jenner Thanksgiving family portrait was NOT photobombed -- turns out the random dude in camo is super tight with Kanye West.

Our Kardashian sources tell us the guy's name is Sakiya Sandifer and he's practically family. He grew up with Kanye in Chicago, and they co-authored "Thank You and You're Welcome" ... the 2009 book of sayings that inspired Kanye. He also wrote his own book, "Think Think Think and Think Again."

We're told the thoughtful guy happened to be in L.A. on biz, so Yeezy invited him for turkey dinner.

This wasn't his first rodeo with the fam -- Sakiya was in Kim and Kanye's wedding, and walked Kylie down the aisle.