We present IAC-star/MINNIAC, a code to recover the age of stars of a complex stellar population system, like a galaxy. It uses a genetic algorithm to minimize a \chi2 merit function comparing the star distributions in the observed color-magnitude diagram (CMD) and the CMD of a synthetic stellar population. A parameterization of the CMDs is used, which is the main input of the code. The computation of the synthetic CMD can be done using the code IAC-star. Since this is a quite time consuming step, a method is presented requiring computation of only a single synthetic CMD. IAC-pop/MINNIAC has been run through several consistency tests and has been proved with deep ACS@HST photometry, which first results are present here.