Britney Spears ' boys are all grown up. And it's a concept that even the "Toxic" singer is having a hard time grasping. Days after sons Sean Preston and Jayden James turned 19 and 18, respectively, Britney—who shares her kids with ex-husband Kevin Federline —shared a message marking the milestone.

"This month is my boys’ birthdays," she wrote on Instagram Sept. 16, sharing throwback photos of herself and her kids when they were toddlers. "Happy Birthday babies and I hope you get all your wishes and more !!!" Sean celebrated his birthday on Sept.

14, while his younger brother became a legal adult on Sept. 12. But even though Sean and Jayden are now no longer considered minors in the eyes of the law, Britney is likely to continue her child support payments to Kevin, who is currently living with their sons in Hawaii .

"Child support jurisdiction continues until the minor child reaches the age of 18, or if upon their 18th birthday they have not yet graduated high school, it continues until they graduate high school," Kevin's attorney Mark Vincent Kaplan recently told People , "but in no event later than their 19th birthday." As he explained, "The child support in this case for Jayden is being paid consistent with that law. His graduation for high school will be in November.

" Sean and Jayden relocated to the Aloha State last year to "get away from the L.A. microscope," Kevin's lawyer previously said, though they still "have a desire" to stay connected with Britney .

As Jayde.