Why does he keep on looking at me?

OK,so this has been happening for a while now but now that I have loads of time on my hands to be on Fluther I’m going to ask you this question.There’s this guy that lives on my street,I’m guessing just a little older than me.He doesn’t go to college as he hasn’t taken up higher education ( I know this because my dad was talking about it with my mum,saying how high fees is affecting people etc).
So,whenever I used to go out (or still do) if this guy is there he’ll keep on staring at me.
Not in a bad way,like with hateful eyes or anything like that,but just stare.When I walk to school or walking back home he is there either hanging around the street corner or on his doorstep.He’s never said anything, neither have I but he has once smiled at me.(It wasn’t a nasty or mocking smile,it looked genuine). I feel his eyes following me whenever I leave the house and he’s there.
It’s just confusing as he’s never talked or approached me.
I know for a fact that he isn’t a criminal/dodgy type as his family is quite respectable and his father is friends with my dad.
So,why is this guy so obsessed with assessing my every move?
He also followed me to the park a couple of times but did it in a subtle way.The park is just around the corner and he came a few minutes after me.The reason I don’t want to talk to him is because I’m a little bit freaked out.There’s nothing wrong with him,as I’ve seen and heard him laugh with his mates aroun the neighborhood.
What are your thoughts as to why he does this?