I have no doubt that from an evolutionary point of view what people find attractive are qualities they saw in their parents. Personally I'd draw the line at shagging someone I thought was, even spiritually, my actual mum.
It seems that Johns idea of reincarnation was a little muddled anyway. Given his mum died when Alma was already treading this earth for a good number of years. Makes me think that Cyn's story might not be the whole truth.