Allow me to officially introduce Brienne Aster-Sorenson. She's the second child of James and Emelia, and an extremely rare (in my story world at least) hybrid.

Because it's physically impossible for different taxonomic families to produce viable offspring, marriage is generally within Genus and rarely outside of taxonomic family. James and Emelia's marriage (as a hare and feline) is far outside the norm and as a result they are not able to produce offspring. Or rather, they wouldn't if Emelia weren't the foremost researcher on FOY.

Using FOY, she regressed both an egg and sperm back through the evolutionary ladder until they were close enough to actually produce a viable embryo which she then implanted in her own body to produce a viable offspring. Jaime was the result of this experimentation. Due to the potential ethical problems involved in what she had done, she vowed never to create another child in this manner.

Imagine their surprise when they conceived another child naturally. Perhaps it was some residual FOY from the original pregnancy or it had somehow changed Em's body, but Brienne was born a little over a year after her brother.

Brienne is a very happy child with a doting family (Brock and Bella are godparents and considered "aunt and uncle"), though Jaime is considerably jealous of the attention his sister receives. She is also quite intelligent for her age, displaying the cognitive abilities of a 5 year old at barely over a year in age. She can read, though physical development prevents her from being able to write or to communicate as clearly as she would like to at this point.