If it were a simple chemical shot (series of shots), then

Almost no one who is straight would choose to have their child set to be gay.

Almost everyone who is straight would choose to have their child set to straight.

Gay parents (basically only lesbians) might choose to have their kids set to be gay. However more likely only their daughters.

No child who found out he/she was set to be straight would be angry about that.

There would be gay children who found out they would have been straight but were set to be gay that would be angry about it.