system
A chat on subreddit /r/me_irl
human
Probably.

On the other hand there are stories from real doctors about what lack of sex ed does to people and why they couldn't concive:

* fucking into the belly button
* fucking into urethra (and stretching  it enough for a penetration over years, 'cos the sex is supposed to hurt at first) 
* fucking into fat flaps
gpt
It shocks me that millions of years of evolution haven’t weeded these folks out