Hi, I would really like to know how to get a genetic testing kit. My hatchery is overflowing and I need to find out the carried genetics so I can decide who to sell

The only way to get a genetic testing kit is buying it at the diamond store (it cost like 1,000 diamonds, I think).
If you dont have the diamonds to buy it, you can ask to someone with genetic testing kit to help you with your pets. Theres a lot of players willing to help you with that, and there are some threads created specifically to do so.

Have a nice day~

to add to what Migam have said, while the best way to get a genetic test kit is to go to the diamond shop you can also somtime earn one-time-use testing kits from events but those are very rare, you may get some from the advent calender tho there is no garentee.

The price of the diamond test kit is 1500 dia tho it does drop at 1000 during festivals, even if you decide/cannot buy diamond with real money there is a way to get that item. At your level i recomand using testing thread since you dont have access to most methodes to make gold tho, once you get an higher level you will be able to earn enough gold for trade at the curency exchange. ^-^

Thanks for the advice! I will definitely be giving those methods a try