Table 1.

Characteristics of the female twins

	MZ	DZ
Number of individual twins	306	686
Age, yrs, median (range)	55.9 (36.0, 69.7)	52.1 (24.2, 70.3)
Height, cm, mean (S.D.)	160.9 (5.8)	162.7 (5.7)
Weight, kg, mean (S.D.)	64.4 (10.7)	65.5 (11.6)
DIP OA (Grade 2 or more at any joint),%	29	21
PIP OA (Grade 2 or more at any joint),%	11	8
CMC OA (Grade 2 or more at any joint),%	24	17
Hip OA (Grade 2 or more, either left or right),%	9	9
Knee OA (Grade 2 or more, either left or right),%	23	20

Grade 2 or more—Kellgren and Lawrence score.