The daughter of prominent Dublin estate agent Seán Davin, she is a niece of politician Joan Freeman—a former senator who contested the 2018 Irish presidential election—as well as barrister and television presenter Theresa Lowe.
[1][2] She graduated in 1999 with a degree in architecture from University College Dublin and worked as an architect with a leading firm for a number of years.
[8] She opposed the Protection of Life During Pregnancy Act 2013, legislation proposed after the judgment of the ECHR in A, B and C v Ireland (2010).
In line with the judgment of the Supreme Court of Ireland in the X Case (1992), this permitted abortion where there was a risk to a woman's life from suicide; Steen claimed this was "wrong and unnecessary".
[17] In 2024, Steen campaigned against two proposed amendments to the Constitution of Ireland: the Thirty-ninth Amendment on the Family, which proposed to extend the constitutional definition of family to "other durable relationships" in addition to marriage, and the Fortieth Amendment, on Care, which proposed to remove references to women's "life within the home" and mothers' "duties in the home", and to add a new article on care within the family.