Genetic Testing: A Footnote

by Jay Johansen

Mailing Lists

If you're like me, you're probably on a million mailing lists, getting sales pitches from companies you never heard of for products you have absolutely no use for. (Sometimes I can figure out the chain, like: I subscribed to a science magazine; they passed my name around to other science magazines, one of which was into debunking claims of psychics and the like; and they passed my name to some people who were into "debunking" religion. So now, despite the fact that I am an officer in an organization classified as part of the "Religious Right", I get offers in the mail for atheist magazines and books.)

Right to Life gets on some odd mailing lists too. We get flyers about medical conferences and magazines that have nothing to do with abortion or euthanasia.

A Genetic Testing Lab Flyer

So when we recently got a flyer from a medical testing laboratory, I was about to throw it away along with other such irrelevant mail. But then I started to read it. This company specializes in genetic testing to determine parentage. I presume that their customers are usually women trying to prove that a certain man is the father of her child so she can get a court to order him to pay child support, or a man trying to prove he's the father so he can get custody or visitation rights. (They mention a few other reasons, like wanting to get medical histories.)

The flyer contains this interesting section:

How does the test work?
The test is based upon the principals of inheritance. A child gets one half of his/her genetic makeup from the mother and the other half from the biological father.
The test reveals a control batch of genetic markers from all parties. The genetic markers that the child shares with the mother are first located. Then to determine paternity, the child's remaining markers are compared to the alleged father. If the man is indeed the father, all of the markers that did not match the mom's should match his. If all of the child's remaining markers match the alleged father, evidence is provided that he is the biological father of the child. If they do not match, he is excluded as the biological father of the child.
When the mother is not tested, a larger batch of control makers are revealed from the alleged father and child. If these markers show that the man is contributing half of the genetic makeup of the child, he is given evidence that he is the biological father of the child. If no makers are found to match between the alleged father and child, the man is excluded from being the biological father of the child.

So What?

So what does this have to do with abortion? There's no indication from this company's flyer that they are pro-life. I doubt that the company has taken a position on the issue. They're in the business of genetic testing, not abortion.

Well, there's nothing here that's surprising to anyone who's ever studied genetics. Half of a person's genetic material comes from his mother; half from his father. These genes determine who you are as a person: whether you're male or female, tall or short, black or white, have a long nose or a short nose, etc etc etc. And without getting into the debate on "nature vs nurture", your genes determine a lot about your psychological makeup.

Science is just beginning to be able to read this "genetic code". We can identify the genes, but we're still a long way from understanding what each one does. We know a few: We can recognize male and female and a few genetic disorders like Downs Syndrome. The government has a multi-billion dollar project in the works -- the Human Genome Project -- to try to identify more. But right now, it's like when I see something written in French: I can recognize all the letters, but I don't know what the words mean. Yet technology has progressed to the point where lab technicians can study cell samples and actually identify which characteristics came from your mother and which from your father.

But ... when did the father contribute his share? Okay, stop the giggling in the back of the room there, but yes, that's right. His share was contributed during sexual intercourse. At the instant of conception, all the genetic material that makes up this new being -- half from the mother, half from the father -- was brought together.

What if two people have sexual intercourse while the woman is already pregnant? None of the man's genetic material will be in any way added to the developing child. If it was, genetic testing would not be possible.

What if this couple had a "one night stand", they met in a bar one night, had sexual relations, she became pregnant, but he never saw her again and he never saw the baby at all? Would he then contribute less to the baby's genetic makeup? Of course not. Such a man may not be much of a daddy, but he's still the father. His entire genetic contribution was made in that one brief episode. If this was not so, genetic testing would not be possible.

All the genetic material that makes up a human being was brought together for the first and only time at conception. Of course the child will grow and develop. But nothing new will be added except nutrition and air. (Unless he get's an organ transplant or some such.) It was at the moment of conception that the unique combination of chromosomes that define YOU came into existence. That is when your life began.

If this was not true, genetic testing would not be possible.

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Posted 9 Sep 2000.