A woman has two kids. One is a boy. What are the odds the other is a boy?

However, the "B / B" option has already been covered in the scenario when looking at the first child being male, e.g. B / B.

Discounting this gives 3 possible outcomes
B / G
B / B
G / B

All of which are equally likely to happen. Therefore, its 1/3 chance or 33%.

So it doesn't matter if you're older than your older brother eh?
B/B is not the same as B/B