Replies to '12/25 Parent Trap'

I don't understand why a law has not been put into action to require all new parents to undergo a DNA test to ensure the relationship with the child.  I think this should be done before the father's name is placed on any birth certificate. 

Wouldn't this end the problem!?  Sure, there are lots of problems associated with this topic, but I think madatory DNA testing would prevent many undesirable situations.