It happens, and is probably more likely than for random pairings, especially if they marry male relatives of Windfinders, but if it was even a very likely probability for channeling to breed true, Alviarin's plan would probably not have been treated as a radical theory. IMO, the Aes Sedai are discouraged from having kids (via novice & Accepted indoctrination, if not from any outright restriction or overt pressure on the sisters from Tower or Ajah authorities) in order to keep their interests apart from the world.

It seems that if female channelers were likely to produce channeling daughters, the Tower would encourage or at least be neutral on Aes Sedai having families. The fact that such a heritage is rare explains the antipathy toward families - since the children are not likely to be channelers, they will eventually become estranged from Tower society, which will create a division of interests and loyalties in their mothers.

No matter how you slice it, the percentage as quoted by Jordan, as well as the numbers seen in the books and population proportions indicate that however more likely a channeler is to have the ability in his ancestry or descendants, it is still not something to bet on.