There's a few cousins above them, and a few below. These guys are bang in the middle.
They were born within the space of 10 months - one baby each for my sisters and I. In fact, Jack on the left was present for the birth of my Lola. (That's what happens when you're only a couple of months old and your mum is required for early morning "PUSH!" duty.)
They don't get together very often, but it's fun watching them when they do. The middle crew.