Michael's emotional background -- as the father of six children, five of whom he adopted from foster care to give them the family support they never had -- resonated with Simon, who is a proud and fiercely dedicated father to his 4-year-old son, Eric.
On Wednesday morning, following his soulful rendition of James Bay's "Us" during the second week of the AGT quarterfinals, ET joined Michael's supportive wife Ivey, and their six adorable kids to talk about their inspiring family and their patriarch's powerful performance.
"[We are] so proud of him," Ivey gushed about her husband, who she's been with since high school.
Michael and Ivey welcomed their daughter, Sophie, and lived as a family of three until their little girl was six years old, and she told her parents that she wanted to have brothers. This inspired the couple to turn their hearts toward children in need, and they went on to adopt five boys from foster care, starting with brothers Jared, Chase and Jeriah.
They next adopted their son Sean, who was homeless and living on the streets at one point before being welcomed into the family. Finally, they adopted Rodrigo, whom they nicknamed Rodee, a 9-year-old boy who suffers from cerebral palsy and had a difficult time opening up to anyone before they took him into his family.
It's not hard to understand why Michael's story resonated with Simon as deeply as it did -- and why Simon gave the AGT hopeful his Golden Buzzer earlier this season -- but the tears were still a surprise, especially for Sophie.
"I was super shocked because you always see Simon as a really hard critic, and then to see him relate to dad so much, it was so, so touching for me to see," Sophie shared.
For Michael's young son Jared, Simon's emotional reaction made sense because "they're both fathers."
"And then when my dad sang that song, Simon just got it, and got very emotional," Jared reflected.
'America's Got Talent': Simon Cowell in Tears Over Singer Michael Ketterer's Performance
Michael, a pediatric nurse who lives with his large family in Orange County, Ca., has won over so many viewers with both his selfless dedication to his kids and his beautiful, evocative voice, and his kids feel he deserves to take home the AGT grand prize because of the kind of person and role model he could be for everyone watching.
"I think because he has an amazing story and he's an amazing human being," Sophie explained. "I believe that he is a leader and so for him to win, he would be able to lead even more."
"I think my dad deserves to win because he is a good father and a great person," Chase added. "And his heart is amazing."
His family has been there for both of Michael's performances, and have gotten a chance to meet host Tyra Banks and judge Howie Mandel. However, they haven't gotten a chance to meet Simon yet, but Michael's kids know what they will tell him when they finally do.
"[I would say], 'Thank you for seeing the talent in my dad and [giving him the chance] to show it off," Sophie said.
"I would say thank you for giving my dad the golden buzzer," Shawn sweetly added.
"It's really been surreal," he admitted. "I did not expect the amount of just people wanting to get in touch with me... I had no idea this would happen." For more from Ketterer's emotional interview, check out the video below.