Secularisation, so the push away from religion that promotes a nuclear family allows gay, single parent and reconstituted families to grow
Changes in law such as the divorce reform act, mortgage changes and marriage act allow for gay, cohabitating and single parent families to increase
Changes in women's position such as equal pay act allow for cohabitating, living apart together and dual-earner families to increase
Changes in social attitudes, such as declining stigma about families that are seen as a harm to society such as single parent or gay families, allow for them to increase