A donor conceived woman posed a dilemma recently on a donor conceived forum that I frequent. She said her mother had forbidden her to tell people she is donor conceived. She said her mother felt the topic was her own sex life and her partner's infertility and thus it was their secret to keep. Here is my thought:
It's your origin story and your life, and you have every right to talk about it. You have every right to write about it. You own that story at least as much as your mother does. My mother forbid me to tell anyone I was donor conceived, and I kept the secret for years. But now I talk about it sometimes. Just not to my parents, which I think is a solid compromise. They don't have anything useful to contribute to the conversation anyway.
You aren't your parents' secret keeper. It isn't fair of them to ask that of you. You own everything that happened to you, including where you come from.