User blog comment:EvanDude345rv5/Fairy Tail 353 : Nine Ghost Gate/@comment-94.224.11.125-20131001161633/@comment-7418318-20131001170909

And why would similar magic hint at shared heritage?

Makarov, Ivan and Laxus all have very different magic, despite being family. And Gray only learned his magic after he was split up with his family (or more precicely, after they died).

Sure Ultear and Ur had the same magic, but then Ultear trained specifically to kill Ur and the best way to understand a magic is to learn it yourself.