[Wm Bach]

Why is there such an arugument on this thread that a child's upbringing largely determines his/her choice of religion as a adult?

I don't know. It's self evident, it can be demonstrated empirically, it's common wisdom, and it passes the smell test.

I suppose people will point to periods of social upheaval and forced conversions and argue that that is the norm. People with a weak grip on their own faiths are hyper-sensitive.