Luca is looking more and more like his mother, who's flawless in this makeup-free, bikini-clad selfie. Hilary also shared a cute photo of herself soaking up the sun earlier that day, and was rocking some stylish summer accessories.
When ET sat down with Duff and her sister, Haylie, last year, they revealed that they're both open to having more children. "I mean, we loved growing up with a sibling," Haylie said. "So, you know, I hope that we get siblings and more babies in our family for sure."
Hilary added, "We'd still like to do it together at some point. Try to time that out right."