Genetic data from over 2,000 dogs and owner surveys show that breed does not predict behavior. Science reported April 28 that breed explains only 9% of dog behavioural differences.
In an April 26 news briefing, geneticist Elinor Karlsson of the University of Massachusetts Chan Medical School in Worcester remarked
Geneticists had asked the topic in various ways. In 2019, a study discovered that DNA may explain some breed distinctions, such as poodles and chihuahuas
The team needed genetic and behavior data from many canines to explore individual variance. So they created Darwin's Ark, an open-source database where over 18,000 pet owners surveyed their dogs' features and behavior
The poll contained over 100 questions concerning observable actions, which the researchers classified into eight “behavioral factors,” including human friendliness and biddability.
The researchers obtained genetic data from 2,155 purebred and mixed-breed dogs, including 1,715 Darwin's Ark puppies whose owners supplied saliva swabs.
According to Karlsson lab geneticist Kathleen Morrill, studying mutts helps decouple characteristics. That means on an individual basis, you'll have a better chance of mapping a gene related to your issue.
Despite small dogs' yappiness, size has almost no effect on behavior. Boyko believes that little dogs act worse than large dogs because “I think it's that we typically tolerate poor behavior more in small dogs than we do in big dogs.”