Josh Duhamel and his wife Fergie are proud parents to their adorable 2-year-old son Axl, and it turns out their little boy is taking after his mom quite a bit.

Sitting down with ETonline's Ashley Crossan on Tuesday to promote his upcoming crime drama Lost in the Sun, the 42-year-old star opened up about how his son is growing up, developing a personality, and starting to look more and more like Fergie.

"He definitely looks like my wife. I look at those two together and I'm like, 'Wow! that's amazing! I'm not even sure if this is my son!'" Josh said, laughing.

WATCH: Josh Duhamel Gushes About Baby Axl, Says He Wants More Kids

According to Duhamel, while seeing the likeness between his son and his wife is "really beautiful to watch," Axl's personality seems to be a combination of the two of them.

"As far as his personality, I think he really has both of us [but] It's too early to say,” he shared. "He's definitely got a personality, this kid, and it's beautiful."

It looks like his personality is going to shine through when Halloween rolls around this weekend. Duhamel revealed that Axl loves the spooky holiday and can't wait to dress up.

PHOTOS: Celebrity Kids' Cutest Costumes

"He knows what Halloween is and he loves watching his Halloween videos. It's not just five little monkeys jumping on the bed, now it's five little zombies jumping on the bed," he said. "The big question is whether or not he's going to be a construction worker or a Teenage Mutant Ninja Turtle."

No matter what costume he ends up in, it sounds like the kid is going to have one killer Halloween.

Themes of fatherhood and paternal instinct play a big role in Duhamel's upcoming film Lost in the Sun. In the film, he plays a small-time crook who befriends a young orphan boy and the two form a close bond as they commit a string of crimes.

Lost in the Sun hits theaters Nov. 6.

WATCH: Josh Duhamel Shows Off His Adorable Son Flipping Off the Paparazzi