Close-knit family? Seriously, I forget how old my family is. I know my age just about. I have a constant reminder.
honestly, i always forget this kind of important information. the only birthday of anyone that i can remember asides from my own (which i know now mainly from having to fill out forms, i never remembered it as a kid) is my dad's, and that only because it's the day before mine.
I do remember a couple - but the majority are a bit of a blur. I tend to get reminded a few weeks before, though - so I can then forget to get a card and make my excuses. It's just not my thing... I'll probably remember my little nephews - try and be the fave' uncle
I have 3 sisters. 2 older and one younger. We give our daddy a hard time about it. 4 daughters, lolz fail.