It's not just an assertion it's literally backed up with evidence, the study posted clearly shows that various behavoural traits are heritable and that they vary considerably between breeds. You're just confused that's all as you can't seem to grasp that variation within breeds doesn't negate variation between breeds even though it's pretty clearly explained.
Likewise you can't seem to grasp that there can be more than one factor re: the risk here, both bad owners and certain breeds being inherently more risky.
The study you posted shows that an individual dog's direct genetic lineage (heritability) is far more of a factor that just general breed, which is what all the studies you've ignored also assert. The variation between breeds is far less useful as a predictor of behaviour, compared to the commonality between breed types (ie herding dogs, sled dogs, retrieval dogs), since the latter is what dog bloodlines (ie, the genes) have been focussed on selecting. Heritability is why dogs of different breeds can still have similar genetics and similar behaviours, and why those of the same breed can vary so widely.
Here's what an XLB
should be, according to the breed standard:
"The American Bully breed is, first and foremost, a companion, exhibiting confidence with a zest and exuberance for life. Despite its powerful appearance, their demeanor is gentle and friendly. This breed makes an excellent family dog. The ideal American Bully possesses the athleticism to do well in performance events.
Aggressive behavior towards humans is uncharacteristic of the breed, and highly undesirable.
Disqualifications: Viciousness or extreme shyness"
This very notion of heritability, upon which you seem to hinge your argument, is exactly why so many industry professionals stand
against Breed Specific Legislation.
Police dog handlers, crime analysts, veterinarians, biologists, animal behaviourists, geneticists, lawyers, pretty much anyone who works in a dog-related specialty have argued against banning yet another whole breed.
Yes, dogs of any given breed may have bloodlines that may make them dangerous, but that only becomes a problem through the actions and inactions of a bad owner/breeder.
There's nothing stopping us 're-speccing' the XLB bloodlines to a more socially responsible temperament. That's what originally happened with Staffies, until back-street breeders stuck their oar in, and in a few generations the XLB could quite easily end up another 'gentle giant' breed like the four Sennenhunds and the St Bernard.
So, rather than banning the whole breed, get off your collective arses and actually enforce laws that take down the breeders who have ruined this and other breeds.
Turn "Dogs of Peace" from a snide internet remark, back into something genuine and deserved.