There is nothing illogical in ***où** je suis né*.

*Où* can be used with both space and time references and this was already the case with the latin ***[ubi][1]*** from which *où* comes from.

On the other hand, unlike Spanish (*El día **cuando** nací*) or Italian (*Il giorno **cuando** sono nato*), ***quand*** can only be used as a *conjonction de coordination*, e.g.:

> *Ma sœur avait trois ans **quand** je suis né*.

When a relative adverb introduces a time or a location, *où* is used, thus:

> *Le jour **où** je suis né*.


  [1]: http://www.dicolatin.com/FR/LAK/0/UBI/index.htm