The answer is slightly more complicated than you might imagine!
Boars or sows?
Boars are male, sows are female.
You shouldn’t keep boars and sows together unless neutered. They WILL produce babies ( and lots of them! ) and there are already plenty of baby and adult guinea pigs in need of a home.
Boars are slightly more likely to fall out and fight, especially during the hormonal fluctuations of adolescence.
Sows do occasionally fall out but this is much less common.
How many boar guinea pigs should you get?
Despite their reputation for fighting, most boar guinea pigs do benefit from company.
The most peaceful boar pairing is father and son, or unrelated older boar with younger boar. This is because they will not be going through the same hormonal fluctuations at the same time and are therefore less likely to fight.
Two brothers from the same litter can work, but they need to be watched for signs of bullying.
Unrelated boar pairs of a similar age, rarely make a good pairing.
How many sow guinea pigs should you get?
Two sows will usually live together without too much trouble.
Two sisters from the same litter are ideal, as is a mum and daughter pairing.
Two unrelated sows can also get along well, provided they are bonded carefully.
Three sows is also workable, but a group of four tends to work out best.
In all cases having the largest cage possible is the best way to minimise the risk of fall outs and fighting, as it allows your guinea pigs to have their own space.