In regards to ligers/tigons \>Male ligers are consequently sterile, while female ligers are not. In regards to mules \>The different structure and number usually prevents the chromosomes from pairing up properly and creating successful embryos, rendering most mules infertile. Sure, there might be *some* which are not infertile, but in most cases, hybrids suffer from infertility and many othet health problems, and this is true with humans as well. Fun fact: Parents of mixed-race children can not donate bone marrow to their own children due to genetic imcompatibility. Here is one such case: https://www.cityofhope.org/hope-inside/minority-and-mixed-race-bone-marrow-donation So yeah, race is more than just "skin-deep", in fact, if you wish the best for your children's health, pick a pardner of your own race.