If you limit the domain to religion, I would agree that the majority of conversions involve an epiphany. Heck, from what I've read, every conversion to fundamentalist Christian has involved a strongly emotional and relatively fast conversion.
However, this isn't true of conversions to atheism. Some of the experiences of conversion to atheism that I have read have taken a long and meandering path that didn't involve anything that might be called an epiphany.
And when it comes to science, I can personally attest to being forced to accept position I didn't like by weight of evidence. Such situation don't involve the joy of discovery and understanding that comes with most science.
Jay