Four boys, born in 1954 as uniovular quadruplets, live in Wroclaw, Poland. This is a unique case in the world. Their uniovularity was proved as a result of serological analyses.

Despite the fact that one of the boys was seriously injured during the labor (he suffered from one-sided paresis and deafness) and lived in special conditions, all the boys are identical and they develop identically.

Genetic factors seem to be more important, in the shaping of the phenotype, than the influence of environment.