In relation with normal human behaviour I am "anti-social". Personally I know I am just different-social which is great for me.
I've been emailing a few people of late whom I don't know that well. And shockingly those gmail contacts started popping up in my gtalk list. The reason was gmails default setting of over-friendly behaviour. If you want more privacy then you need to disable the "Auto-add suggested contacts" feature in chat as described in this help page