Its not that normal, but It's ok, but still you can't marry your cousin because it's illegal. But still, it okay for you to fall in love with your cousin
Honestly, I can't say it either way if it is or isn't normal. But I can say, from experience, that it happens. You are not alone in that respect. I have just come out of that same exact situation,...
get to know them better, make some memories, take some pictures, and force yourself.
Answer
You cannot force yourself to love someone you don't love. I don't care how hard you try or what you do.
You can't make someone love you, they either do or they dont.
You can use manipulation to make someone be and stay with you - but that is for big time losers. Don't be a loser.