Designer Baby

The new controversial issue has aroused since the adaption of new science and technology. Embryos. The idea is that people can have the choice to implant sexual reproduction cells into a woman's uterus. But the problem that was faced is that parents had children that suffered a disorder and decided to have a "test-tube" baby that genetically matched their child with the disorder that could possibly save their first child. I believe that this decision isn't ethically wrong because I believe they have the right intentions. That the parents decision isn't for selfish way s but for common good and love. This choice saves lives and why is that wrong?