We've had confirmation for a few months now that Kaladin's mother Hesina had a Lighteyed parent.
Seems simple enough. There was some speculation early on about who she, and by connection Kaladin, was related to, but no one had evidence to supply so it was all being discussed frivolously.
I may have just discovered Hesina's relative though through a single line in Oathbringer.
Setting: the castle rescue attempt in Part Three with Kaladin and Elhokar moving down the final hallway leading to the Queen. (Page 811 in the Hardcover)
This is the clue. Hesina and Aesudan, the queen of Alethkar were related. (Personal guess: Hesina is Aesudan's Aunt) Kaladin is a relative to the Crown.
I also think this leads into why Aesudan was worried that the Almighty was displeased with her. She was hiding the fact that she had darkeyed parentage. According to the Vorin religion, all lighteyes are born to rule and are superior to the darkeyes. If it became known that one of her Grand?parents was darkeyed, she could lose standing among the nobility. It's easy to see how an Ardent could have found out and used the information to influence her behavior.