Like a lot of you, my interest started quite young.
I can't remember if there was a specific "trigger" but a lot of my earliest memories revolve around peeing. As a child, we'd go fishing a lot or lifting peat (a type of turf that's burned for energy like coal would be in certain parts of Scotland) and of course, working outside in a rural area, no bathrooms were available. So it was normal to see people disappearing behind bushes or rocks to relieve themselves and no-one really batted an eye cos it was just the done thing.
It was the same with my friends too. When I was about 7 or 8, my