The dangers of people abusing eugenics far outweigh its potential benefits. The creation of modified human embryos and gene editing can lead to creating humans that are defined as perfect by the parents. Parents modifying their children can lead to designer babies that are dictated by the parents’ preferences rather than nature. This could lead to a societal separation between humans that are genetically modified to have perfect health and physical enhancements versus those that do not.  Designer babies would cause inequalities between enhanced and unenhanced groups. This inequality would be unethical since it creates an opportunity gap between enhanced and natural children. As a result, people who cannot enhance their children would land at society's lowest rung. The advent of designer babies would lead to serious negative consequences. Society would immediately look down upon anyone with a disability because they are not as perfect as a genetically modified child. It would also lead to less diversity. Therefore, the practice of eugenics is unethical.
There is nothing wrong with parents preferring specific traits over another as long as they are not motivated by prejudice against other people with different traits. If there is not any coercion or influence from society, the preference of a parent about what their child should look like is not unethical. This is comparable to potential parents that decide to become pregnant via sperm donor. A sperm donor is typically asked to submit photos of themselves throughout their life, medical history, a voice recording, and other personal information to help inform the potential parent think about what their child would be like. If parents are able to pick and choose certain features in a sperm donor, it is ethical for parents to have the ability to alter a child they have conceived.
[P1] Eugenics can create designer babies. [P2] Designer babies will lead to inequality in society. [P3] Inequality is unethical. [P4] Therefore, eugenics is unethical.