The Genetic Animals Configuration file is called genetic-animals-common.toml, it can be found in your minecraft file inside the config file. The config file can be used to set which of the Genetic Animals spawn, if the vanilla animals still spawn or not, how long pregnancies should last in ticks, if genders have an effect on breeding mechanics, and how quickly or slowly animals become hungry.
How to open the config
First you will want to run minecraft at least once after you install the mod. If you do not, genetic-animals-common.toml will not have generated and there will be nothing for you to find.
Open your file explorer and type %appdata% in the address bar and press enter. You should see a folder named .minecraft appear amongst other folders. Open the .minecraft folder and look for a folder called config. Open the config folder and look for a file called genetic-animals-common.toml, you will want to open it with either notepad or notepad++ but any text editor will do.
About the config
Omnigender is a setting that changes genders from purely cosmetic to have effect on breeding and the ability to produce eggs, milk and children.
If omnigenders is true animals will breed the same as they do in unmodded minecraft, males and females can fall pregnant, lay eggs or make milk. Genetically if you are breeding two diploid animals together the animal that is acting as the haploid parent will only pass on the genes it inherited from its diploid parent on the sex chromosome mimicking the inheritance pattern it would have had if it was instead born as the haploid gender. If two haploid animals are bred together things get a little more odd for inheritance of the sex chromosome, both parents only have one set each so they pass their exact copies on to their diploid offspring while haploid offspring inherit and exact copy of their acting diploid parent's sex chromosome. Which parent gets which role genetically is first based on if the pair is male/female. If the pair is male/female the baby will inherit from its parent in the same way it normally would regardless of who births it or lays their egg. If both parents are of matching ploidy the animal that is serving a roll it wouldn't normally acts as the opposite ploidy to its partner.
If omnigender is false you will need a male and a female to breed animals. Only the female will lay eggs, produce milk, and carry pregnancies. Genetically everything works in the same way as it would in real life.
Gestation time is counted in ticks, 24000 ticks is equal to 1 minecraft day. To change how long an animal is pregnant you set their gestation time to any number from 100 (which is 5 seconds) to any large number you want. This can be used to make pregnancy practically instant or make pregnancies match the length of time the would take in real life or match pregnancy time to the progression of seasons if you have a seasons mod