Many people have the unfortunate experience of growing up with an overbearing mother. Mothers don't become overbearing out of any kind of desire to be purposefully smothering or controlling. Instead, a number of issues or experiences in a woman's background exert influences on her that cause her to act in an overbearing manner toward her children.
If a woman has a terrible experience with a man -- for instance, one who cheats on her, abuses her or ultimately leaves her -- this creates feelings that may be expressed as being overbearing toward a child. In a way, the mother tries to hold the child to impossible standards as a result of the failures of the husband or boyfriend as a man.
When a mother has multiple children, she has several chances to see her dreams for her children born out. A single child in the family could end up with all of the hopes that a mother might have for her children's future pinned on him. This results in a mother exerting intense pressure on the child to succeed and meet her expectations.
Many mothers are overbearing to a small degree. Others take it so far that it borders on emotional abuse. This type of mother is often parenting in this way because she suffers from some sort of personality disorder. Someone who suffers from a dependent, narcissistic, borderline or histrionic personality disorder could easily end up becoming an overbearing mother because of the characteristics of her condition.
A woman who was abandoned by her own parents as a child is likely to fear that type of abandonment by loved ones for much of her life. This leads to the fear of her own children abandoning her. As a result, the mother tries to overcompensate for those fears by impressing herself onto every facet of her children's lives. This often has the opposite effect that the mother wants and creates children who resent their mothers.