It used to be extremely rare to see expat families with kids and now when I'm in CM if I go to any overpriced farang food or one of the shopping malls I will see them.
What are they doing here I wonder. They look like middle class people with and often have large families. Chiang Mai has changed widely over the last 20 years but job options are still not great. If the mom and dad were both teachers I think they would struggle to live the middle class life in Thailand and raise their 2,3,3,4 kids.