Science Questions

I've heard that bone marrow transplants can cause havoc with DNA testing. Is this the case, and if so, how can the problem be resolved? Ethe in Suffolk

You're right. A bone marrow transplant can cause a problem because what you essentially become is a mixture of two people. Someone takes away your normal bone marrow and replaces it with the bone marrow of somebody else in order to make up for the damage caused by your own bone marrow. This means that you potentially leave behind two DNA fingerprints at a crime scene and could even implicate your donor.

December 2005