I have a colleague who is probably about 5 years older, faculty, and had been working on a project that I'm supposed to take over. It took months to make email contact with her, she didn't really apologize for that, and then I concentrated on other projects because I found her long email response time (and associated traits) difficult to deal with. Plus she is beautiful and well-dressed with pictures of her beautiful, well-dressed kid all over her office, and assorted baby equipment.
And I find the project daunting in tedious ways (i.e., it's a time-consuming new trendy method, and it's not clear that all the time put into the method yields much better work than things I already know or other things I could learn).
But I came back to the project, though, because I like the PI and I wanted the PI to be happy with me.
This colleague is difficult in all the ways you can imagine. And yet I had an "after school special" type breakthrough with her when I noticed no pictures of a significant other in her office. Just lots of kid pictures. And no ring on her wedding ring finger, just a ring on the engagement finger that looks nothing like an engagement ring. Or wedding ring, for that matter.
So if she is difficult to deal with maybe that is part of why. And baby equipment in the office could be that she is a single mom without a backup in case the child is sick. Who knows.