Table 1

Demographic details of the twins studied

Monozygotic twins (n=1856)Dizygotic twins (n=2064)p Value
p values are corrected for relatedness of the twins.
*Mean (range).
†Excess alcohol intake defined as >28 units per week for a man and >21 units per week for a woman.
GORD, gastro-oesophageal reflux disease; HRT, hormone replacement therapy; GI, gastrointestinal.
Age (y)51 (19–81)*52 (20–82)*0.13
At least weekly GORD symptoms18%18%0.98
Body mass index (kg/m2)25 (14–47)*25 (15–54)*0.01
Ever smoked36%45%<0.01
Excess alcohol†5%6%0.54
Anticholinergic drug therapy7%6%0.18
Oral contraceptive or HRT24%26%0.17
Parental family history of upper GI disease26%24%0.15
Right handed88%88%0.92