HeredityGeneticsElephantiasisDiseases in TwinsHistory, 19th CenturyTwins, MonozygoticTwins, DizygoticSwedenEnvironmentRisk FactorsGenetic Predisposition to DiseaseGenes, RecessivePhenotypeFamily HealthQuestionnairesPedigreeSex FactorsGenes, DominantAge FactorsGenetic LinkagePrevalenceGenetic VariationBiological EvolutionCohort StudiesGenotypePolymorphism, Single NucleotideReproducibility of ResultsWeights and Measures