What effect does the foundation of the house have on the house?

Hello. Your father was right. Foundation is very important when building a house. The foundation bears all the pressures that support the whole building. The foundation of your neighbor's house is higher than yours, so because the foundations of your two houses are not on the same level, your neighbor's building will gradually press against your house because of gravity. It was not so obvious at first, but it will become more obvious after a while.