My guess would be a linkage with something else as you say. Look for example at the Russian domestication of silver foxes which was done very deliberately, and

My guess would be a linkage with something else as you say. Look for example at the Russian domestication of silver foxes which was done very deliberately, and bred for less aggressiveness, yet it caused physical changes in appearance like dog-like ears and tails: https://en.wikipedia.org/wiki/Domesticated_silver_fox https://en.wikipedia.org/wiki/Domesticated_silver_fox