Years ago you could classify family as a blood relative, even in professional places. In the novel Spidersilk, the main character Mark touches on the concept of referring to someone as a blood relative and how it almost seems primitive to refer to someone as that because of how far we have come medically. We've known for a long time that DNA is what biologically connects us to relatives and can even link us to some ancestors from way back. It is easily compared to a coding system if you want to think technologically. Blood is made up of so many components that stating someone is a blood relative is quite a vast statement. You can't claim everyone with the same blood type as you a relative can you?

To check out a case where DNA transformed a woman's view of blood relatives follow this link:

http://www.nytimes.com/2012/01/24/us/with-dna-testing-adoptees-find-a-way-to-connect-with-family.html?_r=0