Many of us are gullible and will believe many things without question.
A major problem in our culture is the clash of belief systems. Science is a method which has been shown to be best at understanding the physical world. Current scientific knowledge is not absolute. Our understandings of things changes over time. Scientists continue asking questions. Newton was brilliant, but had no tools with which to understand gravity. Einstein had to bring his ideas to the fore and mostly the Relativity theories have been better predictors of many phenomena than Newton's. Not everyone who calls themselves a scientist is right about this or that thing which they discuss. Individual scientists are human beings with egos and a desire to be right. They are fallible. But when one looks at the total contributions of science to our understanding and capacities, it is enormous. Science is a belief system which allows for correction and change when new evidence is found.
Religious belief systems are generally not open to question and evolve slowly not as much through changes in knowledge, but through the death of the previous generation of imams, priests, ministers, and popes. While science has served the war machines, religion has spawned many wars.
There may not be any structures in our bodies which are different from heterosexuals. I believe there is genetic involvement; in the last ten years our understanding of the way genes work has become much more sophisticated. Evolution may proceed much faster than we had previously thought because the change in gene expressions may be modified by the length of time a fetus in utero being bathed in neurochemicals, by various minor changes in the timing of various events in the development process.
Biologists have catalogued at least 1500 species which have some homosexual expression especially in birds and mammals. Our cousins, the bonobo, the chimp, the gorilla, the orangutan, all have some male-male and female-female sexual interaction.