It's unlikely that this is a major contributing factor. German laws are extremely tenant-friendly, there is no social stigma associated with renting, and rentin

It's unlikely that this is a major contributing factor. German laws are extremely tenant-friendly, there is no social stigma associated with renting, and renting vs. owning is often a lifestyle choice rather than one explained by income (according to a recent study, a great many Germans could afford a home of their own, but choose to rent, anyway). Keep in mind that even Angela Merkel is among those who rent, even though between her income and that of her husband (who is a tenured professor), they could easily afford a pretty nice home. The low birthrate is primarily driven by college-educated women having few or no children (over 30% of all German women who were born between 1964 and 1968 and had a college degree did not have any children). It has historically been difficult to be a working mother in Germany; it was both more challenging (school being out at lunchtime) and society frowned upon you being a working mother. This has slowly been changing; reunification happened and East German women weren't having any of this nonsense; politicians realized that the net effect was that the fertility rate dropped; and the abortion debate and a subsequent judgement by the Constitutional Court forced legislation that made having children easier. As a result, it is now a whole lot easier to be a parent (single or married, male or female) than it used to be. This did at least stabilize the fertility rate, which had been dropping before. While nominally, Germany's fertility rate is 1.4, this does not account for the fact that the great majority of German children are being born after their mothers reach the age of thirty; current estimates set the actual fertility rate -- i.e. the average number of children a woman has over her lifetime -- at 1.6. More importantly, this number did stabilize in the aughts and has actually been increasing since then for college-educated women.