Mothers
The psychodynamic tradition has been criticized for blaming mothers. Reich and Lowen both attributed the bulk of neurotic and schizoid traits to failures in nurture by mothers. To see this as blaming mothers requires however the belief that all behavior and results stem from individuals direct use of the will. But life is bigger than any one person's use or over-use of the the will.
Consider the following metaphor:
If one thinks of a infant as a young plant, and his parents and the entire community as a watering can, it seems reasonable to think of the mother as the spout. If water fails to come out the spout, then possibly the spout is clogged to some degree, but it is very likely that the can as a whole is empty. A spout can do nothing about that. A mother than hasn't received love and support from her partner, is like a spout that is trying to water a plant with an empty can behind her. One can avoid blaming the spout, but it would be irresponsible to ignore that the young plant is getting no water and it's growth is hampered.
Despite the role it might play in sexism, it seems inescapable to conclude that biology and development makes the role of a mother to an infant unique. But while the roles of mother, father, and extended family in nurture are assymetrical, the responsibility should not be.