In Book 4 of the Wheel of Time, Rand al'Thor sees the history of his bloodline from the trip to Rhuidean, and then learns from the Aiel Wise Ones how he came to be born on the slopes of Dragonmount. At the time, however, the Wise Ones do not know that
his mother was Tigraine Mantear, Daughter-Heir of Andor before Morgase.
He does know, however, from the Wise Ones that she left an older child behind when she fled to the Aiel Wastes, so he at least knows he has a half-brother somewhere. Of course, knowing the first spoiler above, we as readers also know that this half-brother is actually
Galadedrid Damodred, later Lord Captain Commander of the Children of Light. He is also the nephew of Moraine Damodred.
Does Rand ever find out about this relationship, or for that matter does he ever learn of his mother's true identity before her adoption by the Aiel?