The cadet branch of a not very prestigious German princely family, Alexander was nevertheless the nephew both of King Frederick I of Württemberg (via his father) and of King Leopold I of Belgium (via his mother).
Membru a unei ramurii a unei nu foarte prestigioase familii princiare germane, Alexandru a fost totuși nepotul regelui Frederic I de Württemberg (prin tatăl său) și a regelui Leopold I al Belgiei (prin mama sa).