Abstract: After their complete sequentiation, genomes are clusterized in genes families, the members of which share a significant similarity in their sequences (and often in the structures of their proteic products) but they are often playing different biological roles. When there is such a relationship between two genes, they are called paralogs. It is of general believe, that paralogs genesis is due to an iterate mechanism of gene duplication with subsequent modification of the copies. In a previous work describing a method to reconstruct the history of genes families, a simulator of genes families was introduced in order to bypass the lack of experimental data about genes families history. Working with these simulated data, some interesting features concerning real biological families has been found. Nevertheless, they have not been explored, since they were too far from the main subject of that paper. In the present work, a simulator similar to that used in the above cited paper has been developed, and many different synthetic data have been generated. The simulation strategy, the biological foundation of it and the comparison between simulated and real sequences are discussed in detail in the poster.