That is intriguing. It would depend on which weight- and size-affecting genetic variants Nigel inherited. In a size prediction model we are working on releasing, Nigel is predicted to be calf-high in height relative to an average person, which is in line with his reported height but doesn’t reveal much about weight.
As the APBT call is quite low (5% is our threshold for likely real, based on mix simulations), there is probably another breed that we cannot call yet in Nigel’s ancestry. The other sub-threshold call that we didn’t report (almost certainly not real) is 1% American Cocker Spaniel. The algorithm is trying to find a match, and I think it’s come up short for that 10%.
That said, the breed standard weights for those tiny breeds are quite low, but from my experience as an owner of a hefty pet Papillon, and a daintier one who has put on some weight in his older age, sometimes the pet population of a breed has more variation in size and weight than the show population.