They came up with two big questions that have surprising predictive power:
1.) Do you have daughters?
2.) Does your wife work outside the home? (Probably couched in more neutral language like "Oh, what does your wife do for a living?")
[The women in question were director/VP level, and so were directing this toward CEOs and C-level execs. Presumably they'd be asked of your direct boss. Both questions can be easily worked into basic rapport-building smalltalk, i.e. you don't directly ask them this in the interview, you just casually inquire about their family. Also, this assumes a male boss; the conversation mostly ignored the question of female bosses, other than to note that women who had to fight hard to get where they are during the 70s and 80s can be surprisingly tyrannical towards younger women coming up.]
The daughter effect has been pretty well-documented in the media [1][2]; it appears that even the most sexist men want their daughters to succeed, and that rubs off in how they treat women in the workplace. (See eg. Ivanna vs. Ivanka Trump.) The reason for asking about whether the wife works outside the home is that in two-career couples, the husband necessarily needs to take on a larger share of the housework & childcare, which makes them more sympathetic to the constraints & sacrifices that a working mother has to make.
[1] http://www.telegraph.co.uk/men/relationships/fatherhood/1093...
[2] https://www.fastcompany.com/3032432/why-men-with-daughters-m...