Genetic, maternal and placental factors in the association between birth weight and physical fitness: a longitudinal twin study. oleh Robbert N H Touwslager, Marij Gielen, Frans E S Tan, Antonius L M Mulder, Willem J M Gerver, Luc J Zimmermann, Alfons J H M Houben, Maurice P Zeegers, Catherine Derom, Robert Vlietinck, Hermine H Maes, Coen D A Stehouwer, Martine Thomis