Simpson shared a new photo of the 13-year-old on Instagram Monday.
Ashlee Simpson and Pete Wentz's son, Bronx, is a whole teenager! Ashlee took to Instagram Monday to share a photo of the 13-year-old, and the internet and his aunt, Tracee Ellis Ross, were shocked by how much the teen has grown up.
"London dinner dates with my loves 🤍," Ashlee captioned the photo slideshow, which began with a selfie of her and Bronx and included some adorable snaps of her husband, Evan Ross, and their daughter, Jagger, 6.
"Omg Bronx is a full adult 😮," celebrity hairstylist Marissa Marino wrote, with Aunt Tracee commenting, "@ashleesimpsonross oh my Bronx looks so beautiful and grown up. We were just together. How!"
Ashlee's mom also commented on the photo of her grandkids, calling them "gorgeous."
"I mean how gorgeous are my grandkids? 🥰," Tina Simpson wrote.
Meanwhile, fans couldn't help but notice how much the 13-year-old looks like his rocker dad, with one writing, "Holy crap! Bronx is really looking like his Dad, nowadays. Wow! Growing up fast!," and another calling the pair twins, "He looks exactly like Pete! Twins."
In November, Ashlee shared a special tribute to Bronx, in honor of him officially becoming a teenager.
"This is 13. Happy birthday Bronx! You are the coolest teenager. I LOVE YOU. I LOVE YOU. I LOVE YOU," she wrote, alongside a black-and-white photo of her and the teen.
Evan also shared a birthday post celebrating his stepson, writing, ""BRONX HAPPY BIRTHDAY KING! LOVE U."
Ashlee and Pete split in 2011, with the "Pieces of Me" singer going on to marry Evan in 2014. In addition to Jagger, the couple shares 1-year-old son Ziggy together.