@Mor - In some ways I wish we didn't have these kinds of DNA tests. Particularly paternity DNA testing. I think the parent should be considered the one who raised the child. It always horrifies me when I hear people joking about men who ended up raising someone who wasn't their blood for years, not realizing it. I like to think that it doesn't matter either way. Blood doesn't matter when it comes to parental responsibility.
Of course, some people might not be willing to care for a child that can't be proved to be theirs in the first place so there are definitely times when the testing can come in handy. I just wish there wasn't so much emphasis on it.