Puberty turns you into a hormone bomb. For most of history 40 was very old, and humans probably did most of their reproducing as soon as they could.

Which is fine if you want a culture of young animals. But the issue with age of consent is that while some adults are horny, others - especially those called paedophiles - are violent, abusive and predatory. So at the very least it's more likely to be a bad idea than not, because child-adult sex includes a huge power imbalance. And at worst it puts children and teens in literal physical danger.

In the UK the problem isn't that some people have sex with children, but that there's a shocking amount of evidence that abuse is systemic, with children being removed from relatively functional families by secret courts (when did those appear?) and put into a 'care' system just so they can be abused and possibly even murdered with impunity.

Worse, there's seem clear evidence of collusion among the establishment, with some very odd bahaviour by certain police, judges, lawyers, politicians, and local councillors - and numerous reports that when police investigations get too enthusiastic, officers are moved on and told to cool off.

Kids being hormone bombs comes nowhere close to justifying any of this.