The idea that Chekov, Uhura, Spock and Scotty never had children of their own is hard to swallow -- one or two, maybe, but half the cast? They aren't monks.
Perhaps not, but STAR TREK does seem to demand a high price of its Bridge Crew characters. Consider Captain Kirk's observation in THE FINAL FRONTIER -
bless its cotton socks, all five of them! - where he reminds Dr. McCoy, "other people have families, Bones. Not us." Now, admittedly, there is room for interpretation, considering the generality of such a statement. This is where context becomes so important, and as such, what Kirk seems to be implying is that if STARFLEET wanted you to have a spouse, it would've issued you one.
Consider how, in
STAR TREK: The Next Generation, Commander William T. Riker didn't marry the love of his life until he was well into middle-age. Chief O'Brien, on the other hand, did get married, as it was the only way to show us his life outside of the Transporter Room. And though Keiko did have her little moments here and there, even the occassional episode focusing on her, she was mainly there to make Mrs. O'Brien's son Myles' life miserable. In fact, even this took a backseat in DS9, to O'Brien's bromance with Dr. Bashir.
And then there's Saavik who's only semblence of Family Life is the implication that she's pregnant with Genesis-Spock's Pon Farr Child, only to be broomed under the carpet so that Proper Spock can resume his own bromance on the ENTERPRISE-A. Keeping STAR TREK heroes single for their Life or Death struggles and "Babe" or "Hunk" of the Week romances is really The Nature of the Beast, here. Seeing these characters after many decades as old people with these unannounced children from who knows what significant other, or cloning proceedure ... there's no hype in that.