In theory, another cause overriding class completely could be true. But the other suggested selection factors from you- class, education, looks, income - are ex

In theory, another cause overriding class completely could be true. But the other suggested selection factors from you- class, education, looks, income - are exactly those that were controlled for. Sure, it could be that people marry by IP address, or ZIP code, or name first and foremost (over looks, class, income and education!), but it seems highly unlikely.