The Good Lord Above decides your gender/sex at the moment of conception. Your DNA (XX for females and XY for males) is fixed at that time. Fortunately, your DNA is your DNA. It cannot be changed, ever. Hormones and disfiguring surgery may change your outward appearance but your DNA is fixed forever.
Males are males and females are females forever. God has spoken.
DNA can, and does change.
Thankfully it's not too common, but when it does, it's called a (genetic) mutation. [1] [2]. One of the nastier mutations in DNA, often times an "acquired" mutation, leads to cancer. [3]
XXX and XXY? People may not be born “gay,” but what of the developmental changes during puberty? Are they possibly born to become “gay”?