The fourth house is ruled by Cancer and the Moon and deals heavily with things of a familial sort. The ancients believed that this was the true beginning of the house structure, that a chart began at the cusp of the fourth house and went around until it finished in the third house. This might be because the fourth house symbolizes the beginning of life as well as the end.
It affects early life, especially time spent in the home. The home is a big part of the fourth house, as well as immediate family, mainly the two parents. Parental influence is heavily emphasized here. The fourth house also establishes what our support structure is like; it represents our stabilizing forces. It is the things we can fall back on if things go awry.
