How many people would be enough to make the odds of  birthday match at least 50-50?

Guess the answer and then read the following paragraph;

You have to stay with the explanation for a while to finally get it.

By an amazing coincidence my sister, Cathy, and my Aunt Vere have the same birthday: April 4 Actually, it’s not so amazing. In any extended family with enough siblings, aunts, uncles and cousins, you’d expect at least one such birthday coincidence. Certainly, if there are 366 people in the family — more relatives than days of the year — they can’t all have different birthdays, so a match is guaranteed in a family this big. (Or if you’re worried about leap year, make it 367.) But suppose we don’t insist on absolute certainty. A classic puzzle called the “birthday problem” asks: How many people would be enough to make the odds of a match at least 50-50? The answer, just 23 people, comes as a shock to most of us the first time we hear it. Partly that’s because it’s so much less than 366. But it’s also because we tend to mistake the question for one about ourselves. My birthday.

To read explanation click on article below:

http://opinionator.blogs.nytimes.com/2012/10/01/its-my-birthday-too-yeah/?emc=eta1