Severus Snape Revealed?

     If I enter the realm of speculation... All the Wizarding families (except, apparently, the Gaunts) appear to be interrelated. I think that the argument might have been the same as Vernon was using, that he would not pay for Severus (as Vernon argued against Harry) to go to a school to learn parlour tricks, or something to that effect. I think that the Malfoys are cousin to Eileen, and that she approached them for help. Severus might have spent a bit of time with them when he was younger (and of course his father would to have approved) and that Lucius taught Severus much of what he had learned of the Dark arts.
     I also think that the restriction against underage wizardry must be a relatively recent thing/ Petunia's comments to Harry about coming home with frogspawn in her pocket and turning teacups into mice--the latter would have had her thrown out from school, had the restriction been in place. Now, why do you think they enacted that restriction? Is it because many of Lord Voldemort's supporters were taught the Dark Arts by him from a very early (pre-Hogwarts) age?