Originally Posted by

**paulrb** Is this problem different though? The siblings aren't identical objects; they're distinct people who were born at different times. It may be more like flipping a penny and a quarter.

EDIT: Shortly after typing this I think I figured it out. Since we *are* told one of the coins landed on heads, there is a 1/2 chance the quarter may NOT land on tails, since it landed on heads. There is also a 1/2 chance the penny may NOT land on tails, since it landed heads. Therefore, each of those possibilities should only count half.