George Kittle wasn't always the hulking, 250-pound tight end that set the NFL single-season receiving mark for a the position in just his second NFL season.
When he showed up at the University of Iowa, Kittle was a 6-foot-2, 185-pound high school wide receiver with a strong work ethic.
It was in Iowa City that Kittle's body underwent a dramatic transformation.
"If you look at any of his high school photos, it will blow your mind," Kittle's mom Jan said.
"He was scrawny when he came to Iowa," Kittle's wife Claire said. "But I think that's kind of just how a lot of people are. So they grow into their body and they become the man that they're supposed to be."
"He certainly embraced our program, he worked very hard," Iowa Strength and Conditioning coach Chris Doyle told NBC Sports Bay Area. "Had to change his eating habits and change his lifestyle from that regard to kind of grow into just the process of becoming a Division I football player."
In addition to growing several inches during his time with the Hawkeyes, Kittle put on a whopping 35 pounds during his college career.
"It's overwhelming every single time I see him," Emma Kittle, George's older sister, said. "Because he's still George, and like my little brother. But like physically, he is a man."
He certainly plays like a man on the field, as the 26-year-old has blossomed into one of the NFL's top tight ends, even earning a second-team All-Pro designation after his breakout 2018 season.
The Kittle family certainly is not short on impressive athletes, as his father Bruce was also a tight end at Iowa and sister Emma was a Division I volleyball player at Iowa and Oklahoma. His mother Jan lettered in both basketball and softball at Drake University.
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While puberty may have set in a little later than most for George, his dedication to his craft has manifested itself as he now stands as the No. 1 receiving option on an undefeated 49ers team.
"I've witnessed everything that he's done so far and like all the hard work," Emma said. "And so to see him succeeding at this level is like, he was born to do this. He was born to have the spotlight on him. He was born to have this type of pressure, like to carry people to work this hard."
How 49ers' George Kittle went from 'scrawny' receiver to elite tight end originally appeared on NBC Sports Bay Area