It’s a product of Marxist thought and presuppositions to believe that they are “born that way”.
Marxist materialism assumes that humans and their behaviors are nothing more than matter in motion and that they really have no choice but to react in specific ways to given inputs.
The left has intentionally suppressed data from studies showing that homosexual tendencies among those sexually abused as children and those raised in same-sex households are much higher than in the general population.
It is not outside the realm of possibility that an individual is born with a predisposition towards some type of behavior or development of some malady. But, a blanket assumption that when a person is born their genetic code determines all aspects of human behavior is preposterous. This ideology completely disregards that human beings are capable of self-determination. Try proposing this to a liberal, though.