Who's your daddy?

Once a year, I teach a case-based discussion section in the medical genetics course for the 2nd year med students at the University of Washington.  Each year, there is an anomalous result in one of the cases that has several potential explanations.  We encourage the students to think through the possible explanations...and one of them is non-paternity.  That case sticks out in my mind, because one year, a student suggested that I was being sexist by suggesting that non-paternity was a possibility (i.e., if I bring up non-paternity...I must propose non-maternity as an option as well).  The class laughed and another student pointed out that generally maternity is a little more difficult to fake than paternity.  Now I look back on this with some amusement. 

Over the past decade, (non)paternity has really been in the public eye - via Jerry Springer and other daytime TV, via court room drama, and via the increasing availability of cheap paternity testing.  In my clinical genetics training, an oft quoted number was that ~5% of individuals in a clinic were not fathered by the person who is ostensibly their father.  I've never been able to track down the primary reference for this; however, estimates in the literature range from a minimum of ~1% to ~20%.  Regardless of the specific number, it is a substantial fraction of people.  The beginning of an era of personalized direct-to-consumer genomics that may be utilized by a substantial fraction of the population may transform the way we think about this issue.  At the very least, if companies like 23andMe and deCODE Genetics are successful in getting large numbers of families to utilize their genotyping services, there will be more...umm...transparency brought to this issue. 

I'm confident that these companies have spent a lot of time thinking about this issue, and I'm not suggesting that it is a reason to regulate or ban the personalized genomic testing by any means.  Nevertheless, inadvertent demonstration of nonpaternity is another way in which the personalized genomics revolution will affect the social fabric of our world.

Comments

[Mr. Gunn]

Yeah, they've thought about it as far as making you read a notice that says you might discover something unpleasant.

One thing not being mentioned is the need for physician education so when all these people start running to their doctor saying, "Doctor, I have a mutation in CYP3A, what should I do?" the doctor knows how to respond.

[Emilia Liz]

Studies of non-paternity from representative samples (not, for example, men who are being tested for paternity) have shown rates ranging from below 1% to 12%. So I suspect the true rate is somewhere between 1% to 5%. Which is still a large number of people, but much below the much-quoted 10%.