Dear Chair of Biology Department,
I encountered one of your former employees on Facebook and do you know what she was saying? Do you? That women don't have Y chromosomes! Which we all know to be a primary school level understanding of biology which science has moved on from.
Please fire her immediately. I know she's already retired, but if you really cared you'd build a time machine, go back a few years, and fire her then. And also make her write "I am an evil bigot" on the board in the lecture theater 100 times.
If you don't do this I will assume that you want my child to die. No love.
A Concerned Parent"