Originally Posted by
Aurabolt
...Check my OP (very first post in this thread). That was one of the scenarios I mentioned.
The liklihood of Kael'Thas having a bastard would depend on when and where we're talking about. If it was before he went to Dalaran to study then yeah I'd say the chances are pretty high he could have had kids, likely with another Sindorei on that note. It's unlikely he made time while he was in Dalaran since his only implied love interest--Jaina--wasn't interested and was also an unofficial rival student of his, too. It's unlikely it was immediately after the Scourge invasion since we know what he was doing from then until he went to Outland. That would be the most likely time Kael'Thas could have had to get someone--likely another Sindorei pregnant with his child and him not knowing about it before he died and was Fel Rezzed. By the time Silvermoon branded him a traitor, anyone who happened to have his child or was pregnant with his child would have likely gone into hiding.
Agewise, a child born after the Scourge Invasion would be 12 to 14 years old now. If they were born before the Third War, they could be of age now though. As you said though, their father's identity could be kept a closely guarded secret off the bat to protect their lives. Usually something to the effect "Your father died before you were born" or "He died when you were a baby." Kael'Thas was a Mage of considerable skill even before he went to Dalaran. Any kids of his would have a strong magical affinity to say the least.