Conclusions: In a large cohort of twins that included almost 35,000 individuals, the self-reported overall prevalence of Scheuermann disease was 2.8% and the male-to-female ratio was close to 2:1. Because the pairwise and probandwise concordance and the odds ratio were two to three times higher in monozygotic than in dizygotic twins and the heritability was high, we concluded that there is a major genetic contribution to the etiology of Scheuermann disease.

Of course this is again self reportage so we have no idea how good this conclusion actually is.

Can someone find out the ratio of identical to fraternal in this large Danish cohort? That would cut right to the chase on certain issues. I am betting the ratio is WAY off which means all these published papers are WAY off.

Don't believe me... check of the Olsen Twins and their "reasons" they use to conclude they are fraternal. No reason to think this is unusual.