No, we are not "born atheist" - nor "born agnostic" either
Occasionally on discussion boards, the question is raised "How did you come to disbelieve?" Some people respond with a testimony of their journey to atheism or agnosticism, but almost invariably, someone will reply with something like "We are all inherently born atheist."
No. We are not!
We are born essentially without knowledge of the world. With newborns lacking knowledge, we could argue that a newborn is inherently agnostic rather than atheistic. But we won't do that either. Agnostic or atheist is a foolish claim in that context. Both terms relate to at least a small understanding of the concept of god. Newborns don't have it. Lacking the concept of a deity, atheist and agnostic are irrelevant terms. It would be equally irrelevant to assign any religious belief system to a newborn child
We are born, not with a position on whether a deity exists or not, but a growing desire to know. Learning is what is inherent in us. What we learn is largely what those around us teach us. Whether we, as children, start out as believers or non-believers depends on what we are taught. As in large part a child's desire to have clear answers makes "I don't know" an unacceptable response, children have an unfortunate predisposition to believe those who say they do have an answer - the answer being God.
Whether we have the ability to later move away from learned childhood beliefs depends in large part, how well we were taught to think.
Don't rely on the claim "We are all born non-believers," particularly if you have children. It does not work that way. You have to teach children disbelief - and I don't particularly care whether you teach them agnosticism or atheism. But disbelief must be taught. Just as the children of others are taught religious belief. We must teach our kids disbelief to inoculate them from the beliefs they will encounter in others as they grow up. And we must teach them how to think; how assess the claims of others also to inoculate them from the beliefs they will encounter.
"Born atheist" is a pernicious claim. Don't believe it. Disbelief is learned, just as belief is.