Allowing adult son to move back in? What is fair?

[Anonymous]

I'm 50, and grew up in a rural area. We lived on a farm with my grandparents while I was growing up, and so did both of my parents. My father, and both of my grandfather's were the youngest, stayed home, took on the farm, and took care of the elderly parents. I left home, went to college, and graduate school, but still lived at home on and off between schooling and jobs into my 20's. I knew I was always welcome, and so will be my children in my home when they are young adults, if they need a place to stay while they get on their feet.