Are you close to your half-sibilings?

When i was 10 my dad remarried(without telling me) and had a baby with my stepmom. I didn't think i would love the little boy as much as i do but we just were close since i met him. Now he's almost 4 and im 14 and we are as close as can be! Im closer to him than i am with my 9 year old sister! Is this wierd or are you supposed to be close to your half-sibilings? Im just wondering because my family is always looking down on me because of it.