Swiss Mix - Chapter 201-225 (Revised)
They record marriages and births, and genetic information, and medical histories, so couples don't accidentally breed when both individuals are both prone to the same diseases or problems - like heart disease, or cancer.
Red Twilight Demon of the Flowers
"you came out here to avoid accidentally breeding with someone, it is fridge and it looks to me like some of your gear was damaged on the way here. i am low on mana. i didn't make it here unscathed either.