Just as, when surnames were first coming into use, the son,
John, of a man named
Robin could become known as
John Robinson, so the son of a man named
Adam could become known as Adamson or, in a more slurred version,
Addison. (
Robin's daughter,
Sally, would be identified as "
Robin's
Sally" until she married
Fred, when she became "
Fred's
Sally". Her children would take their father's name as a matter of course.)
Of course, once surnames became generally used, all of
John Robinson's own sons and daughters would be Firstname Robinson. At this point, I suppose, the surname stopped meaning "son of" and started meaning "descendant of".
I think that most parents give their children names they like rather than names with an appealing meaning. At present it is fashionable to use surnames as given names for both boys and girls. A girl named
Addison isn't said to be male, any more than a girl named
Melanie "should" have dark hair rather than blonde.