The 34-year-old actress has always been close to Joshua, who starred with her in television series Dark Angel back in 2001. To mark Sunday's occasion, Jessica treated fans to an adorable snap from their family album. The image showed Jessica sticking out her tongue and crossing her eyes at the camera, while her hands lean on a smiling Joshua's hip as their father photobombed his kids.

"Happy #nationalsiblingday @joshuaalba -love you my lil bro. With our dad @markdalba," Jessica captioned the shot.

Jessica wasn't the only star to mark National Sibling Day with a throwback shot.

Blake Lively, who now has a daughter with husband Ryan Reynolds, grew up as one of five children - she has a brother, a half-brother and two half-sisters.

In a snap of the brood posing up, along with other people, Blake joked: "Happy national sibling day, Yes, our parents are breeders."

High School Musical star Ashley Tisdale enjoyed a blast from the past too when she posted a shot with sister Jennifer. The pair are seen wearing matching outfits and red accessories in their hair, but while Jennifer is beaming in delight, Ashley looks less than impressed.

"#happysiblingsday @jenkellytisdale I love you so much even though sometimes it might not seem like it. Like in this picture...." Ashley joked.

Sarah Jessica Parker shared a throwback of a different kind by posting a shot of late singer/actress Judy Garland and her siblings - who found fame as The Gumm Sisters.

Meanwhile, Jessica Simpson posted a more up to date shot with her sister Ashlee, while hotel heiress Paris Hilton shared a snap of her and her siblings with the Easter Bunny, writing: "Happy #NationalSiblingsDay @BarronHilton @NickyHilton @ConradHilton #SiblingsGoals."