Hi!
Boars that grow up with sows around are usually struggling a lot less although even then things can get rather dodgy during the teenage months, especially with dominant boars! If in the least doubt, rather keep them apart!
I am lucky in that my own boar pair in my piggy room is very laid back with Nosgan not interested in sows and his sidekick Nye being a very happy-go-lucky chap although they required several separations whenever there was a strong sow season going on while Nye went through his teenage months. They are both neutered, not because it is making a difference in their reaction (it certainly didn't!), but because I cannot risk any accidents from a chance encounter. And they live on a table above the ground floor pens to keep them out of any pheromone storms when several sows come into season at once.
However, what you cannot do is introducing sows into a boars-only environment; sow pheromones for boars that are not used to them are recipe for disaster and can lead to fights and fall-outs.
Ideally you keep boars and sows out of sight and out of reach of pheromones. On the lawn in fresh air, the distance is about a minimum of 2-3 feet with the sows ideally downwind of the boars.
The rule of thumb is:
If you can, keep boars in a different room to sows; at different ends in the same room; ideally above sows (pheromones don't travel upwards) or if next to them with an opaque divider that is higher and wider than the cage - again in order to prevent pheromones from a sow in season to wreak havoc with the boars.
Single boars and single neutered boars living with sows ('husboars') can live in adjoining cages without problems as they have no other boar to fall out with.
Here is information on what neutering does and - more importantly - does NOT:
Neutered / De-sexed Boars And Neutering Operations: Myths And Facts
