As far as I can remember, I do know that my parents both came from the Tang Clan. Also, the fact that both of them were hunted down by the Yan Clan is proof enough that they're both from the same clan. And just to clarify! They may be of the same clan but their lineage is different. That means they're not cousins or siblings for that matter. Even I don't condone such a practice, never.
"Yongrui, this is not the time for jokes... you should get out while you still can. I'll try to outrun them as much as I can. And if I die, just remember that it was in no way your fault. I died because I was weak, that's all there is to it." The Quetzalcoatl said.