I think it depends which business class to an extent and also on which airline.
If it’s long haul with your flat bed seat in a private pod where many of them don’t have an adjacent seat at all and you can shut the “door” and raise the partition (even on your OH) if you’re in the centre two pods.
If it’s the short haul, where the only different is the seat between you and the next person is unoccupied it’s no different to economy really. If we’re talking BA, long or short haul, the seats aren’t the best or configured particularly well. We generally try to avoid BA for this reason.
Other airlines’ business class I’ve experienced are more like BA’s first class. Anyway, we fly a lot and never in business class have I ever been disturbed by children or babies on long or short haul flights. Most people in long haul shut themselves in their pods so you don’t see or hear much at all from the other passengers.
On short haul BC BA flights I have been on flights where other passengers are drinking heavily and standing up together in the isles having long loud drunken conversations.
I’ve also taken a lot of internal flights in India on our travels in economy with lots of young families, and not one person complained or copped an attitude with babies and not one child was irritating. I’d prefer they banned or limited alcohol consumption on flights rather than children
PS the loud snorers in long haul are quite common