I have seen it speculated that having Rey & Kylo Ren being cousins isn’t nearly as dramatic as if they were siblings. I understand this thinking but let me add a little heft to the cousins plot line. If they are cousins then that means their parents are siblings (of course, Leia & Luke) and that potentially becomes much more powerful as Leia desires to save her son (Ben/Kylo) from Snoke while perhaps Luke desires to help his daughter (Rey) destroy Kylo & Snoke.

Potential dynamite ahead.