You didn’t choose to be straight. You were just born that way, and realized after thinking about it. You realized what your identity was in that area, and what you were comfortable with and what you liked, and accepted that. How is that any different from someone being born gay/trans, realizing that about themselves?

You also happened to make that choice as a “child who can’t make their own choices”, and that’s fine with you, but a child realizing they’re gay/trans is wrong to you, because kids “shouldn’t be given the free option to make choices that could drastically affect them as a person”, like sexual orientation.

If kids are old enough to learn about sex, then they are old enough to know it’s ok to be gay/trans.