Maybe your trans ex used to dress up in his mother's clothes and that has influenced her preferences?

My trans-identified ex bought himself a slip that was just like the 50s slips his mother used to wear.  He said that the first time he ever cross-dressed, when he was a child, he put on his mother's slip; his mother discovered him wearing it and punished him.  So to him it was the desired object of clothing.  In other words he fetishized it.  

According to Ray Blanchard (a psychologist and researcher on trans-identified men), cross-dressing autogynephilic men (the majority of today's "transgender women") often begin crossdressing (and masturbating while wearing women's clothing) when they are in early adolescence, in their mothers' or sisters' clothing, which may explain this penchant for buying and wearing clothing like their mothers wore.  
 

The more I tried to understand the sexual element to my ex's crossdressing the more creeped out I got.  The more I understood about it, the more effed up I thought it was.  I'm so glad to be away from it--and him.  

I don't believe there are any healthy "trans" people.  There are always underlying conditions.    

I still haven't figured this out. I don't think my ex is gay, they still look for girl friends. Maybe non-binary? I don't know, this whole gender thing is so hard to separate from the politics of it all. My best guess for my ex is they weren't accepted as a "proper boy" so thought maybe being a woman was the answer? But I never was a "proper girl", and I'm comfortable with being a woman.  I grew up fighting the boxes of what was considered masculine or feminine, eventually figured that since I was female, then by definition, anything I did was feminine. I think the definition of what a woman or a man is supposed to be needs to change. But I really don't understand gender change, it all seems so based on stereotypes.