Britain will allow pre-implantation genetic screening of embryos, to avoid use of those who might develop cancer in adulthood.  This marks an escalation from previous policy, which only allowed screening for fatal childhood diseases.

An ethicist at the British Medical Association denied that this was a stop down the “slippery slope.

“We do not see that today’s decision is moving towards ‘designer babies.’ There is a world of difference between a parent not wanting their child to develop breast cancer and someone wanting a child with blue eyes and blond hair.”

However, it is a world of difference marked by small and debatable gradations:

Some experts fear that as scientists discover genes affecting traits such as obesity, addiction, intelligence or height, a market in elective embryo screening may emerge — backed by evidence that selected children would be healthier, happier and more successful.

There is no clear line to be drawn.  Is it at schizophrenia?  Depression?  Homosexuality?  Some parents would act to prevent any of those, and myriad other conditions, in their child.

And what if the cancer-causing genes could be fixed?  Would that not be preferable to discarding the embryos?

Ultimately, this is another step toward the Gattaca future of genetic improvement of humans.

Incidentally, the article notes that this is not unique to Britain:

Similar embryo screening tests have been used in the United States for years. But because they are not regulated or tracked, no one knows how often they are performed or the full range of conditions being screened for.