For context (hypothetical situation)You were 15 when I was born. When I was 16 you were 31. When I was 21 you were 36. Where do you draw the line? I get your point but if they're consensual adults does it matter?
But 16 isn't seen as adult now in the way it was when I was 16, I could marry, buy cigarettes, get a job and leave education etc. I think 18 is the new 16 in today's society.
You appear to be claiming, in some situations, it's OK for adults to have relationships with children as young as 13. It's not. It's not OK.