Dynamic gene-environment correlation (rGE) may explain one interesting property of heritability coecients: they change during life. They typically become larger!

This means that if you use a sample of adolescent twins and the Falconer model to arrive at an estimate of heritability (A), this estimate will typically be smaller than if you use a sample of older twins. In other words, the relative contribution of genetics to the similarity between twins (established in your research study) will be higher in older twins compared to younger twin samples.

Potentially this could be explained by niche-picking and other types of gene-environment correlation. As you grow up, your genetic programme “unfolds”, causing you to choose certain “niches” in the environment. When they were younger, the twins were exposed to quite dierent environments but as they age, the twins pick the same niches. So, in terms of their behaviour, monozygotic twins become more and more similar with age.

This phenomenon cannot be explained by the Falconer model.

There are several popular Hollywood movies (for example, Divergent, Insurgent, The Giver, The Mortal Instruments, The Hunger Games) that capitalize on the idea of life pre-destination: young people are destined to become specic individuals, and they need to choose wisely to stay true to their pre-destination. To what extent do you think this idea is supported? Is your future “recorded” in your genes, gradually unfolding and creating the illusion that your choices are free?