Genes and Personality

So, do identical twins have the same soul? Or does another soul appear a bit later on? What about Chimera¹, do they have two souls or does one them disappear? Do most² souls never get to be born? If only humans have souls, did Homo Erectus have a soul? What about Neanderthals? What about Australiopithicus (sp?)? At what point did souls start appearing?¹ Chimera occur when there are two fertilised eggs but they combine to form a single individual who's cells do not all have the same genetic code. This is often the case in individuals who have different coloured eyes but can occur in others.
² IIRC, less than 40% of fertilised human eggs go on to actually produce a viable baby.

Here's a transcript of the New Scientist article I learned of it from: http://www.katewerk.com/chimera.html