When taking variance due to measurement error into account (letting A + C+E sum up to 100%), it can be seen that shared environmental influences showed rapid attenuation over time. While explaining 57% of the variance at age 15–17, (almost) no environmental effects were present anymore for the ages 21–32. Genetic factors showed quantitative changes in its influences over time, increasing from 28% at age 15–17 to 58% at age 21–23. Genetic influences remained high at later ages, accounting for still 52% of the variance at age 30–32. The influence of unique environmental influences was small at age 15–17 (15%), but amplified during the next years. At age 30–32 unique environmental influences were as important as additive genetic influences in explaining differences in the CAGE. Interestingly, phenotypic stability and change in the CAGE over time could be largely attributed to additive genetic factors, although at later ages unique environmental factors also contributed to the stability and change.
