SOLVED. YA novel, unknown plane lands with only babies inside. Possible Spoilers. [s]

[Alyssa]

I was read a book in class around 2013 about an unknown plane landing in an airport that was filled with babies, no pilot. Nobody knew where they came from or who they were. The main character, who was one of the babies, got adopted into a family and grew up with them. Then, when he was older (16 years later?) someone contacted all of the kids who were in the plane to get them together. I don't remember much, but I do know the way that they verified that each kid was one of the plane babies was by getting them to touch a rock that had a secret hand scanner. The main character's adopted sister snuck in with him but didn't get caught because she realized what the rock was and hovered her hand over it instead of touching it. I can't remember anything else :(

[MJ]

I wanna read it!

[Alyssa]

I looked into another book read to me in class, and they were by the same author! I feel kind of silly now, I spent months trying to find it. It's called Found by Margaret Peterson Haddix.

[Rainbowheart]

Found for the clickable link.