Barnaby Joyce, a practising Catholic, is expecting a child with his former press secretary, his estranged wife confirmed this week.
Eager to rebuild public trust, independent MP Cathy McGowan said she may introduce legislation modelled on that passed by the U.S. Congress that prohibits relationships between lawmakers and staff.
"Relations between consenting adults are not something you would be justified in seeking to regulate," Turnbull told reporters in Canberra.
Turnbull's centre-right government has a razor-thin one seat majority in parliament and can ill-afford to alienate its traditional conservative voters just over a year out from the next election.
(Reporting by Colin Packham; Editing by Nick Macfie)
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