It means the possibility of keeping your family off from other families.

There must be a separate house, and as far as possible separate rooms, so that at an early period of life the idea of rights to property, the right to things, to privacy, may be instilled." There may be such a thing as too much shelter.

To cover too closely breeds decay.

Are we in danger of covering ourselves and our children too closely from sun and wind and rain, making them weak and less resistant than they should be?
The prevalence of tuberculosis and its cure by fresh air seems to indicate this.

The attempt to gain privacy under prevailing conditions tends this way.
Hitherto students of social economics have usually considered the most pressing problem in the life of the wage-earner to be that of sufficient and suitable food.