Table 1 Distribution of scores (%) for index twins with either a female or male co-twin

0

45.1

47.4

34.2

35.5

55.7

60.6

47.7

48.2

0.5

11.3

11.6

10.0

10.0

17.8

16.7

17.2

17.5

1

8.2

8.9

7.6

8.2

11.1

9.3

12.7

11.5

1.5

6.3

6.1

5.9

6.1

4.8

4.6

6.0

6.2

2

4.8

5.4

5.7

4.7

3.4

2.8

4.8

4.8

2.5

3.2

3.7

4.9

4.8

1.5

1.5

2.3

2.8

3

3.4

3.1

4.0

3.9

1.6

1.2

2.0

1.7

3.5

3.1

2.2

3.5

3.1

0.9

0.6

1.1

1.6

4

2.3

2.0

2.7

2.9

0.6

0.6

0.9

0.9

4.5–5

2.9

2.7

5.4

5.5

0.9

0.5

1.7

1.2

5.5–6

2.5

2.3

3.7

3.6

0.4

0.4

0.9

0.8

6.5–7

1.7

1.2

2.9

2.7

0.3

0.3

0.7

0.8

7.5–8

1.0

0.7

1.9

1.5

0.2

0.1

0.6

0.4

>8

4.0

2.7

7.5

6.9

0.5

0.6

1.4

1.4