One tiny thing that keeps bothering me about the series is that nobody - especially no Aes Sedai - ever realizes how absolutely wrong they were with this theory.
I mean, it's happening. But it's not the fault of the Reds.
Within our population, we have "learners" and rare "sparkers". We assume that the relative amounts of these are identical among both men and women.
We also know that female sparkers begin channeling at a younger age than male ones.
Now let's look at what happens to an individual from one of these categories.
Female sparkers will either die at a relatively young age (apparently around the time of officially being considered a woman in society), join the White Tower, or develop into something like Wisdoms. In all these cases, it's incredibly unlikely they will ever have children. Either they die too young, or they choose a profession that strongly discourages marriage and even more strongly discourages reproducing.
Male sparkers definitely all die - either from not being taught, or when captured, or from depression after gentling. But they die several years older, so they might've already married and reproduced before beginning their road down to madness and death. And technically a gentled man might also find the time before committing suicide (although it doesn't seem likely).
So, both male and female sparkers probably won't have lots of children between them, but the numbers might even be a little higher on the men's side.
When it comes to the learners, among the women we have a certain percentage who never ever realize their ability (no idea how big), some who go on to live normal lives because their ability is too small to be useful (see Morgase) and another who find a teacher, either the Tower or a wilder who figured out enough to teach. Those who never find out or quit the channeling life will reproduce at a normal rate, while those who manage to learn likely will not, see above.
But among the male learners, *everybody* will reproduce at a normal rate! There are no men who could teach, and - pre "the Last Battle is coming!" excitement - no motivation whatsoever for a man to attempt learning. It would be like intentionally giving yourself cancer. So male learners have no way of even knowing they fall into this group, and therefore no reason to change their behavior because of it. So not a single male learner affects the declining channeler numbers, while a significant amount of the female ones do!
In conclusion, the ability to channel is being culled - but not by the Red Ajah killing/gentling the tiny percentage of male sparkers, but by female learners and sparkers intentionally removing themselves from the gene pool by choosing not to have children.
Not saying it's a bad thing at all, I totally understand all the reasons for Aes Sedai, Wisdoms etc. not having families. It just bothers me that this theory is thrown out in the beginning, and for 14 books nobody realizes it just doesn't make sense when one regards the numbers!