title: Reply: Shared environmental effects on multiple sclerosis susceptibility: conflicting evidence from twin studies.
authors.affiliation: 1 Clinical Neuroscience, Karolinska Institutet, Sweden Helga.Westerlind@ki.se.
authors.forename: Helga
authors.initials: H
authors.lastname: Westerlind
authors.affiliation: 2 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Sweden.
authors.forename: Ralf
authors.initials: R
authors.lastname: Kuja-Halkola
authors.affiliation: 1 Clinical Neuroscience, Karolinska Institutet, Sweden3 Department of Mathematics, Royal Institute of Technology (KTH), Sweden.
authors.forename: Ryan
authors.initials: R
authors.lastname: Ramanujam
authors.affiliation: 1 Clinical Neuroscience, Karolinska Institutet, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Hillert
mesh_terms: D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis; D012042:Registries