How to breed pigs?

[Maroliver]

I have 2 pigs. Do I need to set both to allow pregnancy to breed or should one have no pregnancy to simulate a male?

[-Na Shagul-]

There are no sexes as far as animals are concerned, just whether or not they can be pregnant. As for them actually breeding, it's VERY RNG/RARE and people have gone whole games with their animals, specifically pigs, not getting pregnant. If you want more fast, you're much more better off just buying them from Marnie than expecting them to reproduce on their own.