Same reason kids need to be taught about the round earth, physics and other natural phenomena. How crazy that we teach kids that being how they want to be is fine. Come back to me in 40-50 years when your kids stick you into a nursing home because they can’t be bothered to deal with their abusive parent.
Then stop teaching kids about biology, cancer treatment, antidepressants, anti conception or going even further don’t teach them about nuclear weapons, bleach, cyanide, guns, knives. In your logic, kids will definitely want to end their bloodline when learning about the fact that people are allowed to be gay or transgender. You also think kids will shoot up schools because of video games? Surprise surprise, guns, healthcare and climate change will end your precious inbred bloodlines mate, not homosexuality or transgenderism.