So and so’s brother has decided to be gay.
Hint: You don’t just wake up one day and decide to be gay. It’s not like deciding to go on vacation, go back to school, or bring a umbrella with you if they’re forecasting rain. It’s just something you are.
Our ability to admit certain truths about us both to ourselves and others may indeed evolve over time, but you didn’t “decide” to be straight any more than they “decided” to be gay.
There’s a difference and word choices are important.