Both statements are true, and the reason is that most people settle on their adult world-view in adolescence or early adulthood, and very rarely make a major shift in belief (as opposed to minor modifications) thereafter.
While that may be true there are major differences in the stickability of belief and non belief as a person moves from childhood to adulthood.
Virtually no people brought up in a non religious household shift in that view as they become adults. So I think that the data suggests that 97% of children brought up in non religious household stay non religious as adults, with just 3% altering their 'world view' as you put it. And this is despite that fact that non religious households rarely (if ever) actively teach 'non religion' - they don't send their kids to Sunday school where they are actively taught that religion is wrong, they don't send their children to schools where they will be taught to be non religious.
However the same isn't true for children brought up in religious households. Where both parent is religious just 50% of those children retain that 'world view' and become religious as adults. Put it another way half of those children change their 'world view' as they become adults and become non religious.
Where there is one religious parent and one non religious parent just 25% of children stay religious as adults with 75% changing their 'world view' as they become adults and become non religious.
And of course that is despite all that religious upbringing that goes on in those households - attending church, going to Sunday school, being taught to be religious in the home, being sent to faith schools which actively promote a particular religious 'world view' etc etc.
What this tells me is how poor the religious message is - that even if you pump it into kids from birth half (or more) once they become adults will conclude that they don't believe it.