When a woman gives birth to a child, there is obviously no question as to the biological relationship between the baby and the mother. However, this is not always the case with the father of the baby. When a woman is married, her husband is assumed to be the biological father of a child she gives birth to. In such a case, the father does not need to do anything to establish the legal rights and responsibilities that come with being a parent. However, the same is not true for unmarried fathers. You will need to first establish paternity.