One of the arguments that many point to when they say that being gay is a choice is that science cannot point to a particular gene and say people with that gene are gay. They want to do the ten baby test where you line up ten newborns, have doctors test them, and tell you which of the ten are gay.
This theory is fundamentally flawed and I believe is the result of a lack of basic understanding of biology. There are many factors that contribute to what a person becomes. Yes, there are genes. But there are also hormones, diet, physical environment, how active your lifestyle is, and many more things that contribute to you being you. Many things are influenced by a variety of this list.
So where is science today on what makes a person gay? Most credible science finds that attraction to the same sex is not a choice. There is not a consensus on exactly what makes someone gay, but similarities among gay kids across cultures and several physical attributes that are generally but not always different between gay and straight people point that something in the physical and mental development process is different.
It is generally believed but not proven that it is a combination of hormones and genes that make a kid gay. These genes may not be genes in the kid, but possibly genes in the mother too. I am not going to go into the details of this beyond suggestion you read the book Gay, Straight, and the Reasons Why.
This is great and all that there is some limited understanding in the scientific community to what makes someone gay, but we are still years if not decades away from fully understanding this. So how do we respond to the people today who want to point to the ten baby test?
Ideally the person would be willing to have an educated conversation where you could explain what is known today, and point them to some research that they could read on their own and have the information from an independent credible source. However, most people who a going to ask for this test already have their mind made up and no matter how reasonable you are with them are not going to listen to anything you say.
Therefore, I subscribe to the make them take ten seconds and think. It probably will not sow the seed of a question, but maybe 1 out of 100 times it will work. When I am confronted with the ten baby test I very quickly figure out how likely that person is to listen. If I know they will not listen I will respond, “Let me ask you one question in response. You do not necessarily have to agree with me, and you are not going to change my mind. But can you take ten babies, put them in front of a doctor and have the doctor tell you exactly how tall they a going to be?”. Similarly when they do not bring up the ten baby test and instead say show me the gene I respond, “Can you show me the gene that causes cancer? Since you cannot does that mean cancer is a choice?”
I don’t know if this is the best response, but I do know that launching into a spiel on the scientific evidence or your personal experience is generally not going to work. I also think that everyone has already heard the “if being gay is a choice can you point me to the specific time in your life that you chose to be straight?” question and at this point is not going to change anyone’s minds.