Probability is calculated on the ovum rather than the individual; meaning that an individual may potentially be a surrogate mother of a different species, the compatibility is calculated against the ovum to host and the ovum to breeder combined.
The maximum compatible probability is 100%; there are currently no boosters. The order in which probability is calculated and how is as follows, and stacks with each layer: (i.e. calculation for each of the numbered items below (except #4) if the values were 50%, 90%, 150% respectively; the total compatible probability of conception would be the base of 100% multiplied by 50% * 90% * 150% = 67.5% total probability)
Ovum source that is not from the same individual currently hosting the ovum, probability is calculated against the compatibility between species of the ovum and the host; if the species are the same, there would be no variation.(Includes a partnered compatibility boost and any permanently forced and transiently forced compatibility at the time the ovum was generated)
Ovum species is calculated against the individual species that is breeding.(Includes a partnered compatibility boost and any permanently forced and transiently forced compatibility at the time the ovum was generated)
Sum of essence transferred by the breeder over a 5 day period is divided by the total amount of essence the uterus is holding and by the amount that particular species uterus expects (different species have smaller/larger uteruses).(This is the only compatibility calculation which allows a boost up to 200% to offset the previously calculated value; meaning more essence transferred, greater the probability)
If probability is great enough for conception, the same probability value is checked against any potential hybrids that may be conceived between the two species (ovum and breeder); otherwise, the species will remain that of the ovum source species.
