Two sets of people in my family were born on the same date. As for others, even though their birth dates are not exactly the same, they are only two or three days apart. All this can be explained as coincidence, but I'd rather think it's because we were born to be family.
Dad, Jun and Kai were all born on May 27. A lot of their gestures or personalities give us a sense of deja-vu. For example, when Mom took Kai to a bakery this week, Kai couldn't help combing his hair as the wind blew hard. When Mom saw that, her heart skipped a beat. That so reminded her of her dear husband! Obviously, people born on this day give much attention to their appearance. When we told Dad about the story, he laughed, meaning "so true..."
There's no English word for "Yuan-fen," because the word destiny or fate just can't define it. Wikipedia defines it as "the binding force that links two people together in a relationship." I live in a family with strong yuanfen, and that's why we always have a jolly time!