Unfortunately we don’t have their backstories, probably because they are part of the cut content post-S5.
So it depends on when they were all created and if not all at once then in what order.
Did Era 1 begin when White was born, when they expanded to their first colony, or when Yellow, Blue, Pink, or all of the above were created? Was Pink actually Overcooked, or was she just a moron? Were the Diamonds tasked with creating colonies the way all Gems have their roles, or is it something White decided to do and created the others to do, or maybe ordered them to do it while their original purpose was something different?
Ultimately the only truly familial relationships we have are Rutile and the Topazes as sisters, and Amethyst acting like a literal daughter of Pink (which we know was the subject of a cut episode).
I guess it’s left for the fandom to decide until Rebecca writes more. I kind of wish she’d do what the Tenchi Muyo guy did and continue the story unofficially.