There are at least two major weaknesses in this idea:
1) Looking around in the business landscape, it seems clear that 'we' (especially managers) have little understanding of what makes a good leader. ATM the trend is that you have to be the "Alpha Male", hence leadership courses that include white water rafting and other supposedly, very 'male' passtimes. This may impress the sales teams, but I doubt the engineers are in awe over it.
2) Even if we knew what personality traits make a good leader, it is far from clear that there is a simple - or even any - connection between your DNA toolkit and your personality. So far, we seem to have some trouble finding a well defined set of genes for things like skin colour or height, and things like personality are vastly more complex than a simple, physical trait. Plus, of course, we have very limited knowledge (in fact, next to none) about how brain structure maps to personality traits.
So far, we have only just begun to scrape the surface of the genome, the epi-genome and the structure of the nervous system. We are still in the phase where, the more we discover, the more we come to realise how hopelessly inadequate our current understanding still is. It is not impossible that we will understand these areas well, but it will take a while; we will probably be well-established on Mars and beyond long before that day. Going to Mars is, after all, only rocket science.