Firstly, people of different ages have different ways of life. The old people like a quiet, peaceful and regular life whereas the young prefer noises, activities and unrestrained enjoyment. If they live together, old may feel that they are always disturbed and the young may feel that they are often handicapped.
Secondly, people of different generations have different views and values. What is quite normal to the parents may seem to be old-fashioned or wrong to the children. When they live together, they may disagree on matters ranging from minor domestic matters to national and international issues. Consequently, family life may be unpleasant or even unbearable to both the old and the young.
Last but not the least, adult children, like their parents, love independence and freedom, but their parents still take them as children and unintentionally interfere in their affairs. The situation will be worse if the adult children are already married. In this case, the children have already built a new and closed world and any outside interference may lead to conflicts.
From what has been discussed above, we may safely draw the conclusion that if the parents and their adult children do not live together, both the old and the young can enjoy complete independence and freedom, live a life they like, and keep intact their affections for each other.