The DNA test reportedly helps him form the optimal diet/training for his genes.
They advise waiting until later to specialize.
*Scientific paper by Ross Tucker: What makes champions? A review of the relative contribution of genes and training to sporting success
A paperback version is coming out in April with a new chapter and the book has been translated into Russian, Slovak, Portuguese and Japanese (so far).
"But if genetics do play a large role, then should those without an optimal genetic blue print just accept that they will never become champions? ...Throwers should not be so quick to reach that conclusion. Throwing is a niche sport, meaning that the number of participants is quite small. The number who invest substantial time in it is even lower; just think of how many give up the sport at an early age before they reach their potential. This means that genetics play much less of a role and the effort you invest means more."