[TigersEye]

...the whole of an organism is 'arrived at' by a process of developing complexity so the degree of soul connection would likely follow thew same building process.

Perhaps 'the whole of an organism' is arrived at when two incomplete copies of parent DNA fuse together to make one complete, unique and viable copy of DNA. Perhaps that is the magic moment when the immortal soul of a human joins its biological shell.

[MHGinTN]

I prefer to see it that way!