Labour MP Caroline Flint has said it took her years to come to terms with finding out she was illegitimate.
The Don Valley MP revealed she was born to a 17-year-old single mother and has never known who her father is.
She told Radio Times: "I know that, for me, illegitimacy left a mark. For years, even as an MP, I wouldn't talk about being a bastard.
"So many MPs appeared to come from perfect homes, with impressive connections and endless confidence. For years, I kept my story to myself."
Ms Flint, 56, spoke about her childhood as part of a BBC Radio 4 documentary on illegitimacy.
Ms Flint said she found out she was illegitimate by accident when she was ten.
Her mother had married when she was two and Ms Flint discovered a certificate under a bed which stated that the man she thought was her father had in fact adopted her.
Ms Flint said times had changed and there was no longer a stigma attached to being illegitimate.