I don't think this is particularly informative or much of a rebuttal, given that most of those "unaffiliated" were not actually raised atheist or agnostic, and that it would not be particularly surprising that someone raised in an unaffiliated-but-religious environment would end up joining a particular church that they found compatible with the views they were raised with. Without more specific data, I don't think this at all refutes the claim that most people follow the religious traditions and views they are raised with, which I think is very well supported by the geographical distribution of religious belief.
Maybe, but a study entitled “Faith in Flux” issued this week by the Pew Forum on Religion and Public Life questioned nearly 3,000 people and found that most children raised unaffiliated with a religion later chose to join one. Indoctrination be damned. By contrast, only 14 percent of those raised Catholic and 13 percent of those raised Protestant later became unaffiliated.(It should be noted that about a quarter of the unaffiliated identified as atheist or agnostic, and the rest said that they had no particular religion.)
It is still interesting, however, that a majority of the unaffiliated become affiliated, and that the number one reason for that, according to Blow, is that "Most said that they first joined a religion because their spiritual needs were not being met." Blow writes:
As the nonreligious movement picks up steam, it needs do a better job of appealing to the ethereal part of our human exceptionalism — that wondrous, precious part where logic and reason hold little purchase, where love and compassion reign. It’s the part that fears loneliness, craves companionship and needs affirmation and fellowship.Here, I think he makes a good point, though I think the label of "spiritual needs" is a misnomer. This is, I think, the same point I've made in a few posts at this blog, including one on April 29 where I wrote that an overly intellectualized understanding of human beings is a mistake that some atheists make, and one on how Pentecostalism has been tremendously successful with its focus on these other aspects of humanity.
By the way, it's important to note that even if a greater percentage of the nonreligious join religion than vice versa, that doesn't mean that a greater number of the nonreligious join religion than vice versa, and in fact we know that isn't the case from the data that shows that the "unaffiliated" group is the fastest growing group in the U.S.