Some people’s genes make them more likely to get high blood pressure when they eat salty foods, while others don’t — it’s all in their DNA.

Some groups of people, depending on their ancestry or where they’re from, have bodies that react differently to salt—some get a bigger spike in blood pressure when they eat salty food, and that’s because of differences in their genes.

For people with high blood pressure who are white, having certain versions of the SGK1 gene might make their blood pressure more sensitive to salt—but only if they eat a lot of salt. If they eat very little salt, this gene doesn’t seem to affect their blood pressure at all.

Scientists bred rats on salty food and found that some rats got high blood pressure while others didn’t—this shows that whether a rat gets high blood pressure from salt depends on its genes.

If people with high blood pressure switch to a low-sodium salt for three years, their top blood pressure number (systolic) tends to go down—but their genes don’t seem to change how much their bottom number (diastolic) changes.

People of Caucasian descent with high blood pressure who have two copies of certain gene versions tend to see their blood pressure rise more when they eat a lot of salt, and their body produces less of a hormone called renin when they eat little salt—this suggests their genes might make them more sensitive to how much salt they eat.