We all love our dogs for their personalities. Humans as a species tend to hang onto the familiar and think of pets personalities as somewhat fixed.
Dogs like humans change their personalities based on life events.
“When humans go through big changes in life, their personality traits can change. We found that this also happens with dogs – and to a surprisingly large degree,” Author William Chopik, professor of psychology at MSU, Study
“Results showed that dogs’ personalities changed over time based on the quality of their relationships with their owners. A dog’s age in particular had a profound effect on its personality, and while many behaviors can be corrected, those stemming from fear and aggression are more difficult to correct for pet parents. Previous research has shown how dogs can actually read their owners’ facial expressions and become more stressed when they’re in a bad mood.” Article
“The study also showed that dogs young and old tended to have more positive personality traits if they’d taken obedience lessons.” Article
“Older dogs are much harder to train; we found that the ‘sweet spot’ for teaching a dog obedience is around the age of six, when it outgrows its excitable puppy stage but before its too set in its ways.” Study