Blake Lively shared a #TBT photo on Thursday that showed the world she had a past–with Beverly Hills, 90210 heart throb Jason Priestly. Who knew?

In the shot–shared on Instagram–Blake Lively has her arms wrapped tightly around Priestly’s neck.

“#tbt to when Serena Van Der Woodsen and Brandon Walsh were a thing. (Shh don’t tell @robynlively ???)” she captioned it.

A photo posted by Blake Lively (@blakelively) on Dec 11, 2015 at 12:43am PST

As you can see from the #TBT photo, Blake Lively–who is married to actor Ryan Reynolds–was just a little girl when this picture was taken. Her older half-sister, Robyn Lively, dated Jason Priestly for a while way back when, and that’s where the shot originated.

There's more to this throwback pic of Blake Lively and Jason Priestley than meets the eye: https://t.co/tN2gpdLPCm

— Us Weekly (@usweekly) December 12, 2015

Blake Lively’s initial claim to fame came in the role of Serena Van Der Woodsen on the hit CW show Gossip Girl. She received accolades more recently for her role in the film The Age of Adaline, in which she starred opposite Harrison Ford.

You must admit Blake Lively and Jason Priestly look awfully cute together. Do you suppose big sister Robyn had any qualms about sharing her boyfriend with her little sister?