Everything About BB

Hello Kori! I won't say it's impossible, but the chance is extremely small (like 0.0001%).

B's father was killed by a thug and his mother died in a train crash when he was a kid. As for L's parents, we know nothing about them. He came to Wammys when he was 8 while B was certainly not with him. If they were siblings, the only scenario I can come up with was L was the first born, but their parents had to abandon him due to financial problems. But things got better, so when they had Beyond, they kept him.

Nevertheless, in some fans' headcanon, Beyond can even be L's twin brother. I personally believe B does share small similarities with L in appearance, but they don't look like exactly the same. It's so tired to see ppl draw L with a black shirt or red eyes then called them B.