This takes a little time and effort, but owning a pet is a commitment and one that must be taken quite seriously. Six months to one year is commonly when a pig begins to test the waters and take over the household, but it can happen at any age. With family members the pig will often start with the person who appears to be the weakest and most afraid, then work his way up. The most important part of stopping aggressive behavior is overcoming all fear of the pig. Standing up to the pig will greatly reduce his advances.
Most pigs start backing off without any correction.
Pigs are highly intelligent animals and will only engage in a fight if they are confident they will win. If their rival shows fear or weakness, he knows he has won and becomes more aggressive. If the rival does nothing, he continues to test until there is a reaction and the dominance issue is resolved. There are several methods people have used to correct the aggressive pig. Squirt bottles, whips, newspapers, etc.