Somewhere in the back of my mind, I'm sure I've read that in certain circumstances only a son could be apprenticed.
I also recall reading of certain Guilds (Goldsmiths?) that laid down rules as to the financial status/holdings of the parents of any would be apprentice being taken on unless he was the son of the would be master. Of course, it could be that the master automatically exceeded the qualifying conditions by virtue of the Guild he was a member of?
Again, the rules varied over time.
