Answer:
The one discovery that helped scientist gain a better understanding of human genetics, and all the ramifications that came with it, was, the discovery of the structure of DNA molecules by James Watson and Francis Crick.
Explanation:
This discovery, one of the greatest achievments of scientists, especially in the 20th century, opened up the doorway for a lot of new discoveries and scientific development, especially in the field of genetics. This discovery, which took place in 1953, and which was a result of the research carried out by scientists, James Watson and Francis Crick, became a milestone in history, and gave birth to other scientific fields, such as molecular biology. The discovery simply was that these two scientists were the first ones to be able to unravel, and portray, the true nature of the human DNA as a double helix. This has allowed scientists to understand the very basics of human life.