One of the easiest ways to start an argument among people who own dogs as pets is to raise the issue “Which is better, a purebred or a mixed-breed dog?” In such an argument the mixed-breed advocates are apt to bring up the topic of “hybrid vigor”. This refers to the idea that mixed-breed dogs have fewer health problems because of a more diversified gene pool. While it is true that certain purebred dogs can show a number of physical problems which are genetically based, the jury is still out on whether mixed-breed dogs are healthier overall. Thus far the data suggests that mixed-breed dogs can inherit many of the problems associated with each of the breeds that goes into their makeup. So the general consensus seems to be that mixed-breed dogs are no more or less likely to have health issues than their purebred counterparts. However, what about behavioral differences?
Canine Corner, Psychology Today