As part of the repercussions from the recent focus on diversity, people are starting to talk about mentors again—that women need more mentors, that women are needed to fill higher roles in industry so they can better act as mentors to younger women, and that, in general, mentor relationships are important to women. It turns out, though, that there are a number of interesting nuances around the whole issue of women both as mentors and as mentees that complicate these conversations.

A study that helps put some numbers around why the question of female mentoring is so complex is Women as Mentors: Does She or Doesn’t She? A Global Study of Businesswomen and Mentoring, released in March 2014 by Development Dimensions International (DDI). DDI surveyed 318 women executives and found the following:

78 percent of women in senior roles have served as formal mentors at one time or another, but 63 percent haven’t had mentors themselves.

54 percent reported that they have only been asked to be a mentor a few times or less in their career, while 20 percent reported they have never been asked.

71 percent of respondents reported that they always accept invitations to be formal mentors at work.

That last statistic does appear to put to rest one misperception about female-female mentor relationships—the “queen bee” stereotype that comes up a lot in discussions of how women relate to each other in the office.

The “queen bee” is the classic trope about a female boss who can’t deal with the success of female subordinates. Consequently, she sabotages them, due to the perception—rightly or wrongly—that there can be only one successful woman at a company. And while there certainly must be male bosses who can’t deal with the success of male subordinates, somehow those situations never seem to capture the imagination the way the female situations do. Language is significant. Think about it: Is there even a male-male equivalent of the “queen bee” terminology?

The other interesting finding from the study is the significant percentage of senior women who have served as mentors, but who did not themselves have mentors. This suggests that this whole female mentorship thing may be a relatively recent phenomenon, considering the decades that it has taken for today’s senior women to get to where they are now. And the second statistic cited above suggests that women may not be serving as mentors more often in part because they aren’t being asked.

The DDI study, however, is also predicated on a couple of assumptions about women and mentor relationships that just aren’t the case.

That female mentor relationships are primarily woman-woman, as opposed to a man mentoring a woman or a woman mentoring a man. This assumption is limiting for a couple of reasons. For one thing, maybe it’s a good idea for mentors and mentees to be different from each other, rather than cookie cutters in different stages of development. Otherwise, how much can they learn from each other? Second, out of simple demographics, there just aren’t that many women executives out there who can be mentors. If young women develop the perception that, rightly or wrongly, they can only be successful if they have a female mentor, and then they don’t get one, lack of success could become a self-fulfilling prophecy. (Not to mention, if all the senior women are busy being mentors, how are they going to have time to work on their own careers?) That a mentor relationship for a woman is necessarily the same thing as a mentor relationship for a man. Both relationships are called “mentor,” and both include components such as training and feedback. But the mentor relationship for a man apparently includes a significant degree of what some people call sponsorship—that is, speaking up for the guy, making sure he’s being considered for promotions, and so on. For whatever reason, that sponsorship aspect isn’t happening with women. “Men who had a mentor were 93 percent more likely to be put in a mid-management or above positions than men who did not have a mentor,” reports the InPower Women site, discussing research on the phenomenon from Catalyst, a nonprofit organization focused on expanding opportunities for women and business. “Women who had mentors were only 56 percent more likely.”

There’s not any question that mentoring can be valuable, both for the mentor and the mentee. At the same time, organizations don’t want to set up a situation where people who can’t find a mentor can’t get a promotion. If having a mentor is that important, then companies should consider setting up formal mentoring programs to make sure the relationship will be valuable to both participants. A formal program also helps ensure that mentor relationships include the important sponsorship component, for both men and women. Hopefully, the result will be more equitable training for both men and women—with more equitable promotions.