Majority homeownership is a post-1950s thing in the US, corresponding with the beginning of the big drop in the fertility rate; the (temporary) late 1980s surge in homeownership corresponded to the start of the big drop in family formation; the recent drop is from an extremely short term spike and is still above where the late-1980s surge started.

While at any given time homeowners may be more likely than their age-peer contemporaries to start families, aggregate homeownership rates don't show any sign of being a positive contributor to family formation.