This is one of those ever more uncomfortable areas of ethics that are cropping up more often these days as scientific progress outpaces social evolution. It's the kind of thing you need the JCs of this world to handle really - i.e. professional philosophers
In the case of this particular subject, look at this way : a new mother is in the maternity ward and the doctor says to her "I'm afraid your baby has a severe problem - if we don't operate now the child will certainly die. If we do operate, the child will be able to live a perfectly normal healthy life. Do you want us to go ahead with the operation?"
Realistically, how many mothers would say no to that?
Now extrapolate that scenario backwards to embryonic screening - would the same mother have chosen an embryo which would not require surgery at birth?
Every embryo is like a huge random lottery pick, where the probability of any two embryos having exactly the same genetic code is so remote it's not even worth considering. But there's far more to a person than mere genetics of course - babies are not manufactured by machine from blueprints, they are grown from a genetic recipe. And because of this organic growth aspect, no two humans can
ever be identical, not even if they're twins. Heck, there are discrepancies even in one person's body (just look at the pattern of veins on the back of your hands to see that) that are the direct result of having been grown rather than machine-made.
What's my point?
Just that when it comes to the concept of embryo screening, one of the reasons it makes some folk nervous is the "what if" factor of the discarded embryo - i.e. what kind of person would it have grown into? Do I have the right to say which random genetic lottery pick stays and which goes? Maybe the defective embryo I discarded would've grown to be a saint, whereas the defect-free one I chose might grow up to be a tyrant?
What I'm saying is such "what ifs" are completely pointless because of the gazillion factors that go into producing any given human offspring. Simply put, it's impossible to predict what a child will become because the number of possible permutations is incalculable. So it's pointless to speculate on the "what ifs" when you can't ever know what your child will become, no matter whether it's a screened embryo or not.
Human beings pride themselves on possessing freewill. Unlike other critters, we as a species have the ability to pick and choose whatever we like. We can even choose things we know are bad for us, like excessive consumption of alcohol - the choice is indeed ours. We can choose to be good, bad, or indifferent. We can choose to raise brats or angels. But up until now, that complete freedom of choice has been thwarted at the genetic level. Why shouldn't someone want to have a cancer-free child if the option was there for them? If you could ask the child in advance, what do you think they'd say? But as we can't ask that question of the child we've yet to have, it's up to us to make the choice for them - just as we do as parents when we choose what food to feed our children, what language they speak, and even what religion they are brought up with.
We already control our children in every way it's practically imaginable to do so - controlling what genes they get before they're born is merely a logical extension of that process. All parents want the best for their children, and if that means being born without the risk of cancer, how can that be a bad thing?
But this is why the subject is such an ethical minefield : why stop at cancer? Why not have tall kids, or smart kids, or even kids with blue eyes?
I personally have no objection to eliminating defective genes from the human genome just as I have no objection to the fact that human science has made the smallpox virus extinct. If flaws can be corrected and we have the power to correct them, then I believe we should do so. The real problem comes with what is deemed to be "a flaw". Cancer genes are obvious because they are unarguably defective on a biochemical level. But what about conditions such as sickle cell anaemia? It's disadvantageous, certainly...but heterozygous sickle cell carriers are naturally extremely resistant to malaria, so it's a chance plus of an otherwise very negative mutation.
And that's before we even get to the matter of social trends and their possible effect on choice of offspring. After all, we've done it to dogs and cats haven't we? How can the madly bugging face of the needlessly diminutive chiuahua, or the poor bald body of the Sphinx cat be seen as a positive consequence of genetic selection?
I said before that one of the defining characteristics of humanity is our freewill. But there's another singularly human feature in play too : our perversity. It's a done to death yawn-worthy homilie, but nevertheless it is true that with great power comes great responsibility...and to be honest I'm not sure I could trust humanity with that degree of power.
Bottom line is, morally I'm in favour of genetic selection when it comes to removing defective genes from the human genome...but exactly how far the definition of "defective" goes is where the real problem lies.
