In our last piece, we continued our series on the troubling moral consequences of various forms of artificial reproduction technology. From the death of hordes of innocent human embryos to the violation of the sacred marriage commitment, the picture doesn’t look pretty when man tries to play God. But we’re not done yet.

Let’s look at a couple more implications of this vicious technological trend.

5) Gamete donation can cause “accidental incest.”

If you’re a particularly good-looking woman, or a particularly athletic man, or perhaps a mathematical genius or world-class musician, then this century is the century for you. You could earn a chunk of change by selling your gametes to eager customers who want their children to have the genetics that produced your looks or abilities.

You get free money, and parents get amazing children.

Sounds good for all involved, right?

Wrong.

There’s an annoyingly nasty problem that surfaces when you give your gametes away to multiple people: what if those people live in the same community?

Here’s where we must face a deeply troubling implication of gamete donation. If many people in the same community all decide they want a kid that looks like the same super-model or can play football like the same all-star—and so they all buy gametes from the same donor—then genetically speaking, your community will have a bunch of unknowing half-siblings all running around.

And meeting each other. And maybe falling in love and getting married.

We call that incest. “But it’s not on purpose!” Fine. Accidental incest.

The point still stands: the gamete donation industry creates the very real possibility of creating a whole community of incestuous relationships.

This is a truly frightening situation, especially because those involved might have no clue that they are genetically related to those they meet. (Keep in mind that this problem still applies even when gamete customers don’t live in the same community, because some children will likely travel elsewhere when they grow up.)

One obvious reason we avoid incest is because of the possibility of genetic mutations in offspring of siblings. But the deeper reason we’re all repulsed by it is that God has forbidden it, and has ensured that the revulsion of the practice is imprinted into our deepest sensibilities.

This is, yet again, one of those impossibly sticky situations that arises when man messes with the very straightforward, no-ambiguity, natural method of bringing families into the world.

I’m indebted to a mentor of mine for this way of characterizing this startling consequence.

But he isn’t the only one mentioning incest in conversations like this. One advocate—on the other end of the spectrum—has suggested that we rethink the way our natural revulsions influence our laws, and posits that we even rethink the concept of incest itself.

Come to think of it, it sure would make the whole dilemma disappear if we redefined incest, wouldn’t it?

6) A child made according to certain criteria will be evaluated according to those criteria.

To wrap this series up, let’s shift our gaze to the effects of such choices on the children themselves. God made the world such that parents’ genetics inextricably determine their children’s genetics. But He did not make the world such that parents can choose what their children’s genetics turn out to be.

I again draw from the helpful perspective of the President’s Council on Bioethics’ 2003 book Beyond Therapy: Biotechnology and the Pursuit of Happiness.

Think about it this way: the capability to mess with your child’s genetics means your child is no longer the unconditionally accepted gift that God ordained him or her to be. The family is no longer a place where children are the fruitful consequence of marital love, to be joyfully welcomed into the fold no matter how they “turned out.”

Rather, they are a made-to-order product. And if at least part of your child’s existence is the result of your preferences that he meet certain criteria, at least part of your perception of him will be the result of how well he fulfills these criteria.

Try to explain that to your kid once he’s older.

Ultimately, we’ve seen that the gut reaction that “men shouldn’t play God” is not merely an aversion to the unknown or the unconventional. It has real confirmation in the real consequences of man’s meddling in the mysterious act of reproduction.

Man has stuck his scientific fingers into the Pandora’s box of reproduction and unleashed a ghastly series of moral perversions and impossible dilemmas. I’m eerily reminded of God’s assessment of the builders of the Tower of Babel, when it seemed that nothing that man planned to do would be impossible for them.

And I fall back on the response that seems less and less of a cliche the more we look into this field: Only God should play God.