Seriously, is it possible some people just can't touch their toes?

About a year ago I became determined to improve my flexibility and wanted to be able to touch my toes with straight knees as a goal. I know there's more to flexibility than that, but it's a clear measurement milestone that I wanted to achieve.

Well after 3 months of 1on1 yoga sessions and 5 months of 1on1 reformer Pilates with very expensive specialised instructors, I can safely say I'm nowhere close! Straight after a session I definitely feel more flexible and get a bit closer to touching my toes (but still a good 20cm away from the floor), but the next day it feels like I'm back to square one. My hands don't go lower than my knees, which is exactly where I was a year ago. Even one of my instructors, who is still very encouraging, admitted he was surprised by how far I still am from the ground given my work.

I've read a lot of websites and articles saying that for some people it just takes time, but I'm becoming increasingly convinced that there's a subset of us who are just not genetically able to touch our toes. I'm a fairly certain I never could, even as a child. Is there anyone else like this, or anyone who managed to get there after years of work?