It was a great computer. People remember Commodores and Ataris for the games, but the BBC Micro's BASIC implementation was much better, and it had some great software too.
The ancestor thing I guess is because Acorn went on to invent the Acorn RISC Machines architecture, which became Advanced RISC Machines and eventually ARM. So Acorn, which started as a tiny hobbyist company, is behind the processors inside billions of phones and other devices today.