If this gets rubbed over then this won’t cause any damage to the human body. However there is still a gamble involved and at present the use of gene doping carries with it a risk of cancer and other problems. The addition of a new chromosome would avoid this problem, and it would also mean that the expression of these genes could be turned on and off.
One of the moral issues already surrounding designer babies is the price and this can be fairly prohibitive. However this is not the only reason people do not yet use designer babies, or that currently the process has not proven highly popular and there are many more moral and practical issues surrounding the process that have put people off of the use of these methods.
For instance one such moral issue is that it could get rid of our current diversity. The ability to select specific genes and traits would mean that some variations clearly would die out, and this might take away from some aspect of what it is to be ‘human’. At the same time many religious groups see the use of designer babies as ‘playing God’ and are therefore opposed to it on religious grounds.
However there are many positives surrounding research into designer babies too. For instance, though it might result in there being fewer of some types of people, it could also conversely result in there being more types and variations – and it might even save those that would otherwise ‘die out’. It would enable many people to have babies who can’t (just as IVF already does) and it would enable us to have the baby that we chose. Illnesses and mental conditions could be eliminated without resorting to eugenics and we could have the children that we always dreamed of.