Yeah, seems to me the parentage listed on the birth certificate has long been one of the things that’s more about a social role and often not about a biological reality. Factors like “genetic testing isn’t done” and “fertility donors aren’t listed” means the birth certificate has always been more of ‘a lead to follow up when trying to discover,’ than ‘a document of,’ genetic parentage for the kid on it.
But we do need a strong public understanding that you need to be bringing genetic facts with you when you rock up at the genetic disease test doctors.
I’ve started a discussion about birth certificates in general in this thread: http://www.internationalskeptics.com/forums/showthread.php?t=348019