I've seen stats that correlated number of previous partners with divorce risk. But I always wondered if that was a correlation rather than causation (i.e. both of those factors sharing underlying causes).

An obvious example is that a person from a culture where sex before marriage is unacceptable is also from a culture where divorce is frowned upon.

Someone from Uzbekistan told me that a girl can only date one man, and must marry him or her reputation is ruined forever. So when her now-husband wanted to date her, he had to take care to avoid making it official before they were sure to marry.

The US has a lot of subcultures, so I too doubt the usefulness of such studies.

Then again, for some leaving the subculture they know carries a very high social cost. Hopefully new generations will break some of these barbarous traditions.