 Two of Alexander's brothers followed their father's profession – the eldest, Isaac, and Ralph or Raphael – and two others (Moses and Solomon) went into the law, but Alexander instead opted for the navy.Like his brothers, however, he was brought up a Jew but attended St Paul's School, London, and renounced the Jewish faith by publicly receiving the sacrament according to the Anglican rites and thus being able to enter on public careers without impediment from the Test Act.Joining the Navy in 1743 as a midshipman under Captain Edward Pratten on HMS "Suffolk" (70 guns), he passed his examination for lieutenant on 3 December 1747, entering the sloop "Hornet" on 11 December and transferring from there to "Speedwell", another sloop, in the West Indies in spring 1750.