I watched this color cartoon back in school prior to 1995 in the USA, but I'm not sure how old it actually is.
The only scene I remember is a nuclear family (pardon the pun) seen from the rear. The family consists of a father dressed in a blue 1950s suit and fedora, a mom with blonde hair, and a boy. The boy gets a soft drink from a vending machine and sprouts 2 additional arms--to the delight of all three. The view changes and reveals that the mother's head is just a single giant eye and that the father also has 4 arms. There may have been a dog as well, with its own mutations.