How would you feel as a parent towards...

How would you feel as a parent towards your child being transgender? I am asking because i currently follow a transgender music artist on instagram. They were born a female but now they are a male. This person is instagram famous. The guys parents abandoned/ disowned him because of it. I personally feel like if a person believes they were born the wrong gender it shouldn’t matter because it’s what their heart and mind truly believes. I have no problem with transgenders what so ever. I mean yeah i would never date a transgender but i think it’s cool when people aren’t afraid to do what they truly want/ believe in. I also have a cousin who is now a male instead of a female. My cousins parents, grandparents and all of the family seem to be ok with the fact that he is a transgender now. But i don’t understand why parents would disown their children over it. What is your opinion on this?