20 year old, no, wouldn't even consider it. That said, I'm in my late 30s and I recently hit it off with a woman who is only 24 and that feels weird. I could be misreading it but as far as I can tell she's interested in me. It's a work thing, so of course that has its own bucket of complications but basically we just started chatting and kept chatting and she's always kept it going as much as I have, I can get her to laugh and she remembers little details of things we talk about, her body language shifts from office-mode to a more positive relaxed posture, we steal glances at each other from across rooms. Just all those little things where she just as easily could be strictly office friendly and nothing more. So it's all a bit weird. It's cliche and cringe to say it but she genuinely does seem 'mature for her age' and when we chat there's not often moments where I get hit with ah 'oh yeah she's way younger than me'. But it's still a weird thing that I just don't think I can get behind. (Which again, it also being a work thing just adds that other layer of come on, dude)