It seems to me that religion and a belief in God is merely a cultural artefact inherited from those around us. If no one on Earth was religious, would our children seek out some sort of belief in a deity?
I wouldn't put too much time into interpreting his aphorisms, but Wittgenstein's perspective might shed some light on the subject for you.
"As long as there continues to be a verb 'to be' that looks as if it functions in the same way as 'to eat' and 'to drink', as long as we have the adjectives 'identical', 'true', 'false', 'possible', as long as we continue to talk of a river of time, of an expanse of space, etc. etc., people will keep stumbling over the same puzzling difficulties and find themselves staring at something which no explanation seems capable of clearing up. And what's more, this satisfies a longing for transcendence, because in so far as people think they see the 'limits of human understanding', they believe of course that they can see beyond these."
- Ludwig Wittgenstein
"Culture and Value", pg. 15e c.1931
"religion and a belief in God" , have lot of commonalities in one sense, but they are very different in another sense. There are religions that are atheistic and there are leaders of major theistic religions who have expressed skepticism about God.
Regarding the question of the nature of a 'cultural artifact', you'll find extremely strong opposing views among philosophers. In fact one of the biggest clash points between analytic and pragmatist philosophers is about the nature of 'warrant' or justification. There are many pragmatists who make the extreme claim that even 'warrant is a sociological notion' or 'warrant is a cultural artifact'.
So 21st century philosophy cant give any definite answers to your question (I'm assuming that pragmatism has a significant influence here), if at all it can to anything. Regarding your question on children and deities, you should probably ask a child psychologist.
I believe that Religion in the true sense, i.e., questioning the existence of oneself, nature, order and causations and their methodology of work, which is primarily metaphysical, is inborn in every human being. However, Religion in the sense of rituals, prayers and customs, are, to a large extent, cultural artefacts and requires social nurturing.