In his recent book Dr. Roy J. Schepherd states that: “Further information of genetic effects is likely to be derived from comparisons of identical (monozygotic) and fraternal (dizygotic) twins. Gedda (1961) has already shown that identical twins are more likely to have a similar interest in sports than are fraternal twins. It would be interesting to carry out comparisons of maximum oxygen intake and other objective measurements of endurance fitness on the two classes of twins, but this crucial experiment has yet to be completed”. We are very glad to be able to announce here that Dr. Schepherd's wish is being fulfilled within the scope of a wider research project undertaken jointly by the Gregor Mendel Institute for Medical Genetics and Twin Research and the Italian Olympic Committee's Institute of Sports Medicine under the auspices of the Italian Sports Medicine Federation. The studies we have undertaken aim to assess the respective roles of genetic and environmental factors as related to selection and training in sports and physical education. The twin method affords, through a comparison of MZ and DZ within-pair concordances, an assessment of the degree of genetic conditioning in any individual trait. It is quite obvious that the possible influence of training on any given trait is inversely proportional to the degree of genetic conditioning of the same trait. If a given trait, required for a certain type of activity, is completely or almost completely conditioned by the genotype, we should seek those who have inherited it from their parents without wasting time and effort in useless training sessions. As we can see, the scientific information we are seeking has great practical importance in the selection and training of athletes in every single field of sports and physical education.