The demographic situation of families in Germany is characterised by later onset and thus an abbreviation of the reproductive phase of life, the renunciation of family formation or expanding and a still close connection between marriage and family expanding. In this demographic context, the following article examines the initiation and the courses of family formation based on the reasons for having children, the ideal number of children and the ideal age at birth of the first child. As a result, the guiding principle of having children as a matter of course was formulated, since despite all the discussions about the change of the family in Germany having children is still regarded as something completey normal. According to the ideal family size model, the ideal childbearing preferences which were identified exceed the value of two. The ideal desire to have children is limited by high personal demands on material security, which must be fulfilled in order to decide to have a child. This is why the model of materially secured parenthood was formulated on this basis. It is worth pointing out that the ideal age at childbirth is lower than the actual age at the birth of the first child. Early and late births prior to the age of 20 and after the age of 35 are hardly accepted. All in all, four types of families can be distinguished according to the requirements for material security of the formation of a family and the importance of the professional independence of women. While material demands directly reduce the desire to have children, a woman´s demand for professional independence is mediated through a higher ideal age for the formation of a family, which in turn reduces the desire to have children.