Modern Family star Nolan Gould began working on the hit show when he was just 10. Now a teenager, even he is surprised by his growth spurt.
"It's kind of crazy sometimes, I'll see a side by side shot of when I first started the show and how I look now," Gould tells PEOPLE. "It's like a metamorphosis. 'Who is that little curly headed kid right there?' "
The now 15-year-old actor says it's "cool" that he's been able to grow up on the show. And people have noticed his more mature look. Originally, he says, fans on Twitter thought he had been replaced by another actor.
"People were like, 'Did they replace Luke or something? He looks so different,' " Gould says. "Especially this season, because I grew like 3 inches over the summer, my voice deepened and I got a new, older haircut."
Gould thinks its "kinda funny" how longtime viewers of the ABC show, now in its fifth season, have mixed feelings on his character changing before their eyes.
"There's one group on the Internet that hates me growing up. They are like, 'No, our little baby is growing up! Awww Luke!' " he says. "You have the other side which is like the teenage girls who are all into it. They are like, 'Oh yeah, he's getting older, woo!' It's really interesting to see what you find."
Eric McCandless / ABC / Getty; Ethan Miller / Getty