Rocko's Modern Life/WMG

Rocko has undiagnosed Asperger's Syndrome

 * For starters, he is quite nerdy and loves wearing his lucky shirt almost all the time. Secondly, he has a really nasty temper and tends to snap sometimes when annoyed. In one episode, he has a nail-biting problem that may have been a "stim" for him. He's also quite shy and introverted and a little socially awkward. He's very honest like many aspies as well as straight-laced and level-headed while being a little eccentric at the same time.
 * His shirt is a "family shirt" according to the 200 year old Wallaby in O-town.

This is the world if Discord had a chance to rule it.
If the ponies didn't beat Discord this time they would have evolved into random animals who act a lot more like people and things would have settled down, but still be like this.

Explanation for Filbert and Dr. Hutchison's steer son
In the episode where Heffer learned he was adopted his birth father appeared to him in a vision. One thing he said is that he has a lot of children who all resemble Heffer. Some of his children may have been in a relationship with a turtle or cat along the way. Meaning one of Heffer's older siblings (or his father) is a direct relative to Filbert or Dr. Hutchison.
 * Evidence points to Filburt due to the child being born with glasses.
 * This troper always thought it was because Heffer farted on the egg while sitting on it.