more complexity in terms of the number of free slopes that are required. However, visual inspection of Figure 5 indicates that the BIC and AIC preferred trend lines largely overlap. For the genetic contribution, the AIC preferred model implies that the genetic contribution vacillates around the constant value implied by the BIC model. In infancy and adolescence, the estimate of the genetic contribution is slightly lower, and in childhood and adulthood, the estimate is slightly higher. For the environmental contribution, the trend lines overlap nearly perfectly except in old age where the AIC preferred model indicates a slight decline.
