IcelandEnvironmentGenotypeGene-Environment InteractionGenetic Predisposition to DiseaseRisk FactorsBreedingPanicumQuantitative Trait, HeritableSocial EnvironmentModels, GeneticWeaningTwin Studies as TopicGenetic PleiotropyPhenotypeHybrid VigorQuantitative Trait LociCrosses, GeneticAnimal HusbandryGenetic VariationReceptors, Dopamine D4Selection, GeneticPoaceaeSerotonin Plasma Membrane Transport ProteinsEpistasis, GeneticCattleDiseases in TwinsAllelesPolymorphism, GeneticPolymorphism, Single NucleotideTwinsBody WeightChromosome MappingTriticumSeasonsAnalysis of VarianceGenetic MarkersRegression AnalysisModels, StatisticalReproductionLife Change EventsEnvironment DesignLinear ModelsAnimal FeedModels, BiologicalEnvironment, ControlledMolecular Sequence DataPhylogenySequence Analysis, DNAPolymerase Chain ReactionGene Frequency