Ms Lamb addressed the House of Representatives on Wednesday afternoon(February 7).
Federal Labor MP Susan Lamb says she has been unable to access documents to renounce her dual citizenship because her mother left her when she was a child.
"I want to explain to the House why I can't obtain a copy of my parents' marriage certificate. It's a complex and a traumatic story, a story that I don't usually share," she said.
"One day when I was six years old my mum dropped me off at school and she never came back to pick me up."
The member for the Queensland seat of Longman has faced calls from the government to resign because she has no evidence of renouncing her dual British citizenship by descent, and is therefore constitutionally ineligible for parliament.
In a tearful explanation, Ms Lamb has told parliament she was unable to obtain a crucial copy of her parents' marriage certificate, which could clarify her citizenship status, because she no longer has any contact with her mother and her father is dead.
Ms Lamb says she's confident of her position as a federal member.
"Three independent barristers including a retired justice of the federal copurt of Australia have resoundingly agreed that I took all reasonable steps to renounce my citizenship and that I was validly elected to parliament and am eligible to sit in this house. I remain confident I took all reasonable steps to renounce my citizenship and nothing will change."
