Predetermining sex and gender?

I always thought that it should be just fine having (or adopting) a child and allowing them to decide for themself which sex and gender labels they want to use... and how they want to express that choice.

...allowing people to continue the bullshit of polarizing sex, and allowing the people in medicine to further fill peoples heads with LIES? That gets to me. You CAN'T choose the sex and gender of your child!!! CHROMOSOMES DO NOT DETERMINE SEX AND GENDER!