At first, people thought that it is genetics or hereditary because it usually runs in the family. People thought that since it runs in the family, there must be a particular DNA that makes a person homosexual.
Others thought that it is the external environment that makes a person gay. It is thought that the external environment influences a certain person to change his or her gender orientation and sexual preference. Peer pressure is often cited as a cause that makes an individual adapt the preference of his or her group. Many thought that the environment itself makes one homosexual such as having dolls as toys when they are kids make one homosexual.
There are also people who thought that homosexuality begins with having a certain homosexual genes or DNA and then made it a full blown homosexual when one is exposed to environment and having a group that makes a person homosexual.
All of these theorizing seems plausible but experts disagree on this notion about what really causes or makes one gay. They found out through research that neither our genes or environment makes us gay. Scientists claim that homosexuality is neither genetic or external social factors but rather it is the womb that makes one gay. Scientists call it Epigenetic which is the process where DNA expression is influenced by external factors in the environment (not social factors). Specifically, experts argue that
Epigenetic mechanisms can be seen as an added layer of information that clings to our DNA. Epi-marks regulate the expression of genes according to the strength of external cues. Genes are basically the instruction book, while epi-marks direct how those instructions get carried out. For example, they can determine when, where, and how much of a gene gets expressed (Dvorsky, 201). ...