title: Twins and twinning.
authors: J G
authors: JG
authors: Hall
mesh_terms: D005260:Female; D005821:Genetic Techniques; D006801:Humans; D008297:Male; D011247:Pregnancy; D011256:Pregnancy Outcome; D018433:Twin Studies as Topic / Q000379:methods / Q000639:trends; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic / Q000235:genetics