Sexual complementarity of man and woman is the basis of marriage

While the proposed Constitutional amendment is being promoted as being about ‘equality,’ there’s another fundamental question to be decided on May 22.
Should we, as a society, retain a special social institution, ie marriage as it has been understood until now, that specifically recognises the unique significance of sexual complementarity, which is not a doctrinal invention of the Catholic Church or any other religion but is the basic biological fact of nature without which society wouldn’t exist because we ourselves wouldn’t exist?