Just wondering;
Do all different kinds of metahumans have the same DNA-structure??
i.e. can you tell if someone is human or orc by performing a DNA-test??

All life as we understand it, in SR, has the same DNA structure, that is, same compoennts make up the chains. And yes, a DNA test could determine the Meta type of the person, or species, such as parazoolgical

thanks for the quick answer!!

DNA structure and DNA sequence are two different things. As Nikoli has indicated DNA only has one structure really. It is a specific type of molecule and if its structure were different it wouldn't be DNA. The sequences encoded in a DNA molecule are what changes from person to person. A genetic test could detect the specific sequence that codes for a metahuman phenotype, but only if they have already determined which gene that is and its sequence. I am willing to bet that has been done by 2063 in SR.