Assessment criteria 1.2
Q. The table shows concordance for height between monozygotic and dizygotic twin pairs from birth to the age of eight years. A concordance of 1 indicates that the twins are identical in height.
| Concordance for height between | ||
| Age | monozygotic twin pairs | dizygotic twin pairs of the same sex |
| Birth 3 months 6 months 12 months 24 months 3 years 5 years 8 years |
0.62 0.78 0.80 0.86 0.89 0.93 0.94 0.94 |
0.79 0.72 0.67 0.66 0.54 0.56 0.51 0.49 |
- If height were entirely genetically controlled, what concordance would you expect between monozygotic twin pairs? Explain your answer.
- Does data for eight-year-old twins suggest that height is largely controlled by genetic factors? Explain you answer.
- Suggest an explanation for the low concordance at birth for monozygotic twins.
