Manfred Kayser

Professor of forensic molecular biology

Erasmus University Rotterdam, the Netherlands

We have heard about DNA being used as evidence in court. What else can genetics do for forensics?

One of my main interests is in using DNA to predict appearance traits. I combine fundamental research on the genetics of human appearance with applied research such as forensic DNA phenotyping, which is using the prediction of appearance from DNA as a tool in police investigations.

Your latest study focused on stature. How well can you predict a suspect's height from DNA?

We were able to predict extreme height, which is those in the upper 3 percent, with an accuracy of 0.75, where 0.5 is random and 1 is a perfect indicator.

Are there physical traits you can recover more reliably?

The accuracy for human eye and hair color is much higher at 0.9, and chronological age—based on T cell receptors—is the same. But everything else we've looked at is actually much lower than our height accuracy.

What other attributes might be predictable from genetic material?

Skin color is almost certainly next. You can do this now to some degree, mostly by working with ancestry markers, but there are of course variations. Face shape, which would be the holy grail, is in the distant future—we've only found the first five genes, and the effects of those genes are very small. There must be hundreds of genes that affect the face.

Artist Heather Dewey-Hagborg recently made 3-D portraits from DNA she found. Is it possible to make such portraits accurately?

I do believe it's possible in the long term. What I didn't like about her work is that it mixed things that are possible—hair and eye color—with things we can't predict yet, like facial shape, and things we can't predict for certain, like skin color. For these traits she used her artistic skills, and they had nothing to do with science or genetics.