We have squares and we have circles. Now, the squares describe a male individual and the circles describe a female individual. We also have colored squares and circles, and we have uncoloured squares and circles. Now, a colored shape basically describes an individual that has the phenotype for that particular disease and expresses that disease, while the uncooled individual, the uncolored shape, describes individual that does not show that particular phenotype for that particular disease, so they are not affected by that disease. Now, all these individuals, all these shapes found along the same road describe all the individuals that belong to the same exact generation. So, for example, individual one, two, three and four belong to, let's say the P generation.