I don't get it. Wouldn't anyone's chances of marrying any group be higher if we assume they are married at all? Because "being married" is a super set of "being married to a person from X group"?
I think an extreme example might help: if there are 100 software developers but 98 are single, and 2 are married to each other, then 100% of software developers(that are married couples) have married software developers, even if only 2% of all software developers are married at all.
Because "being married" is a smaller superset of "being married to a software developer" than "being alive" is.
It's the same reason there's a higher rate of being married to software developers among people who are married to software developers than there is among the general population.
