I'm a female high school runner, and I completely accept transgender people. However, because of the inherent differences in performance between boys and girls, I feel that, to compete in a female event, a transgender individual should have been treated with hormones so that her testosterone level is not far above that of other females. This would prevent boys who claim to be girls to cheat the system (I doubt this would happen, but many see it as a problem), as taking hormones is an irreversible step to transitioning.
This is a delicate balance; transgender people have the right to participate in sports, contributing to a happy and productive life, but female athletes should not have to compete against other girls with higher testosterone levels.
Running on a team has helped me so much in my life; who am I to deny this benefit to others? Transgender people are bullied, assaulted, killed, and committ suicide at far higher rates than is the general population. If running brings these people joy, let them run, for their lives are difficult enough. As long as they retain no unfair advantage (a.k.a. male levels of testosterone), this high school runner sees no problem in competing against transgender athletes. All of the ones I know are paragons of courage and determination.