A Medal in the Olympics Runs in the Family: A Cohort Study of Performance Heritability in the Games History

Abstract

<b>Introduction:</b> Elite performance in sports is known to be influenced by heritable components, but the magnitude of such an influence has never been quantified. <b>Hypothesis/Objectives:</b> We hypothesized that having a former world-class champion in the family increases the chances of an athlete to repeat the achievement of her or his kinship. We aimed to measure the heritability of a medal in the Olympic Games (OG) among Olympians and to estimate the percentage of the genetic contribution to such a heritance. <b>Study Design:</b> Twin-family study of a retrospective cohort. <b>Methods:</b> All the 125,051 worldwide athletes that have participated in the OG between 1896 and 2012 were included. The expected probability to win a medal in the OG was defined as the frequency of medallists among Olympians without any blood kinship in the OG. This expected probability was compared with the probability to win a medal for Olympians having a kinship (grandparent, aunt/uncle, parent, or siblings) with a former Olympian that was a (1) non-medallist or (2) medallist. The heritability of the genetically determined phenotype (h²) was assessed by probandwise concordance rates among dizygotic (DZ) and monozygotic (MZ) twins (<i>n</i> = 90). <b>Results:</b> The expected probability to win a medal in the OG was 20.4%. No significant difference of medal probability was found in the subgroups of Olympians with a Non-medallist kinship, except among siblings for whom this probability was lower: 13.3% (95% CI 11.2-14.8). The medal probability was significantly greater among Olympians having a kinship with a former Olympic Medallist: 44.4% for niece/nephew (33.7-54.2); 43.4% for offspring (37.4-48.6); 64.8% for siblings (61.2-68.8); 75.5% for DZ twins (63.3-86.6); and 85.7% for MZ twins (63.6-96.9); with significantly greater concordance between MZ than DZ (<i>p</i> = 0.01) and h² estimated at 20.5%. <b>Conclusion:</b> Having a kinship with a former Olympic medallist is associated with a greater probability for an Olympian to also become a medallist, the closer an athlete is genetically to such kinship the greater this probability. Once in the OG, the genetic contribution to win a medal is estimated to be 20.5%.