What will be the biggest benefit from mapping the human genome?

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I'd like to hope it will be the eradication of some of the nastier diseases we humans seem to get. Some explanations of our differences - why do some people like Marmite and some hate it? Also as some form of record as to what our genome is at the moment, so that if/when we evolve further, we will be able to look back at how we were, without all the gaps in knowledge like we have with our ancestors.