So there are genetic and environmental influences on our characteristics. But is it really that simple? Perhaps our genes can influence our environment, or vice versa?

For the purpose of the quiz we have kept it quite straightforward and focused on the relative influences of genes and environment separately. But the more research we do, the more we know that most of our characteristics aren't simple at all! Most of our traits are complex, and influenced by many different genes and many different environmental influences.

Some influences of what we perceive to be 'environmental' actually also have a genetic component. You may have thought of smoking as an environmental component, but whether people quit smoking or persist in their behavior is actually strongly influenced by their genes.

Genes can interact with each other. For example, if gene A contributes a 2% risk, gene B a 3% risk, together they may contribute a higher risk than the simple sum of their risks. These gene-gene interactions are also studied in twin and family studies, but were not discussed in the quiz.

And to make things even more complex there may also be interactions between genes and environment. The effect of a particular environmental factor might depend on someone's genetic make-up. A traumatic life event may be especially influential for people who carry a particular gene variant that makes them susceptible to depression. Our understanding of how gene effects interact, and how gene and environmental factors interact is still relatively poor.

What do you think?

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