Just wondered if anyone knows the legal age for working behind a bar over here in Spain?? Is it different if its a family run business? any help appreciated, thanks & merry christmas

Only going from when this question was asked on another forum and the answer (from a Spanish bar owner) was 18 to be allowed to serve/sell alcohol. This would imply that somebody under the age of 18 might be allowed to serve food products, clean in a bar etc.
The ownership of the bar makes no difference, not sure why you think it would?
I can find no written legal references to the employment of minors in bars in Spain on the internet but would guess that it is probably an EU employment/licensing Law.

The owners' kids of my local bar (waaaay off the beaten track) sometimes
work serving drinks etc when they've finished their homework. At a guess, I'd
reckon they're about 12.
Oh yes - and don't expect a smoke-free environment when you're there, either.

Off topic, but why would anyone expect a smoke free environment in a Spanish bar? The smoking laws are different from the UK, in that owners of bars and restaurants, depending on capacity, are allowed to decide whether to be smoke free or not.

Under the new anti smoking laws, if a bar, below 100m2, wishes to allow smoking, it can.

However no one under the age of 18 is allowed in.

That is the law, but like the rest of the anti smoking law, it is not being enforced.

Tell that to the owners of my local bar.

As I said - it is not enforced - so every bar ignores it.