There are a variety of items on site which have the ability to change the outcome of a breeding, or give you higher chances of receiving a particular offspring result.
Interspecies Potion (allows two pets of different species to breed)
Testosterone Extract (makes the offspring of a breeding more likely to take after the Father)
Estrogen Extract (makes the offspring of a breeding more likely to take after the Mother)
Masculine Essence (makes all offspring male)
Feminine Essence (makes all offspring female)
A pet's fertility stat determines its percentage to breed twins or (vary rarely) triplets! A fertility stat at 0 for both parents means a pet has a very low chance of breeding for twins, and a nearly impossible chance of triplets. These pets will normally produce one offspring, which is the norm. However, you can feed your pet a Fertility Brew in order to permanently raise their fertility stat! Fertility goes all the way up to 100, which gives the pet a 50% chance of twins and a 10% chance of triplets.
Q: What if the two parents have different fertility stats?
A: The chance of twins and triplets is determined by averaging the two parent's stats. For example, a breeding with one parent with a fertility stat of 100 and the other with a stat of 0 would functionally be breeding with a fertility stat of 50.
Q: Are fertility stats breedable?
A: Yes! Fertility stats pass on to their offspring as the average of the two parent's fertility stats. For example, two parents with a fertility stat of 20 each would produce an offspring with 20 fertility. However, if one parent had 100 fertility and the other had 0, the offspring would have about a 50 fertility stat.