Synthetic DNA will still not be alive. It will have to be inserted into a living cell. Life comes from life.
This is gene editing/splicing on steroids. I don’t know what the state of play is currently with regard to human zygotes, but the obvious first tier issue would be a parent (of either sex) who carries the gene for some serious genetic condition. What are the ethics of screening egg or sperm cells prior to fertilization to select one that doesn’t carry the problem gene(s)? Or editing a defective gene and using the “corrected” sperm or egg for fertilization? Are we really morally obligated to NOT correct for conditions like cystic fibrosis or Fanconi’s Anemia if we can edit them out PRIOR to fertilization?
We already have wide acceptance of genetic screening of embryos for multiple conditions, with abortion being the dominant choice in response to a variety of conditions (e.g. Downs Syndrome).
This is not the same thing as creating a highly artificial designer baby selected with multiple desirable traits engineered in. Nor is it the same thing as splicing in genetic coding from other people. It would be a matter of editing out a specific piece of defective coding using a person’s own genetic material. Nor is it the same thing as human cloning, although I would not be surprised if that isn’t being done in secret.
Of course, the next step would be ....
My prediction is that this kind of genetic editing will be embraced by the very same luddites who reject GMO corn, because a precisely controlled edit to make a corn plant toxic to common pests is somehow an offense against Gaia. But these very same people will clamor for the genetic editing of their own children in the hunt to produce perfect babies.