Differential emotional recall with particular gene variant based on ethnicity

The researchers found that, in both groups, people carrying the ADRA2B gene variant [for noradrenaline receptor] were "substantially more likely" to remember both positive and negative pictures than people with other forms of the gene. Neutral images were recalled to the same degree by people with and without the variant.

However, Rwandans with the variant had far higher recall of negative emotional events than the Europeans who carried it – and this was unrelated to whether or not they suffered from post traumatic stress disorder.

So what else is involved? Maybe interaction with other genes? I don't know anything about his field. The blog author asks a couple of intriguing questions regarding consequences to culture.