People of African ancestry almost all have a specific chunk of DNA near a gene called FADS1, and this chunk seems to help control how that gene works.

What we've found so far is that a specific DNA segment near the FADS1 gene appears to play a role in regulating its activity, and this segment is very common in people of African ancestry. Our analysis of the available evidence shows this pattern clearly, based on the data we’ve reviewed [1]. The evidence we’ve reviewed indicates that nearly all individuals with African ancestry carry a 30 kb DNA segment located close to the FADS1 gene. This segment does not sit inside the gene itself but is positioned nearby, and the available data suggest it may influence how the FADS1 gene is expressed — meaning it could help determine how much or how little of the gene’s product is made [1]. The FADS1 gene is involved in processing fats, including essential fatty acids from the diet, so changes in its regulation could affect how the body handles these nutrients. Our current analysis shows strong support for this finding, with 49.0 supporting assertions and no studies or data points contradicting it in the set we examined [1]. While we cannot say definitively how this regulation works at a mechanistic level based on this evidence alone, the pattern across the data we’ve analyzed leans toward a clear association between this DNA segment, FADS1 gene regulation, and its high frequency in African populations. We recognize that genetic research is ongoing, and our understanding may shift as more data become available. At this point, what we can say is that this DNA segment is consistently found in people of African ancestry and is linked to changes in how the FADS1 gene behaves. Practical takeaway: This genetic feature may help explain differences in fat metabolism among populations, but more research is needed to understand its full impact on health.