There are many ways that your family place can help shape you into the person that you are today! For example if you were an only child you are the only person who your parents were looking out for and caring for, so you are more likely used to being the center of attention. Where as if you are one of many children, then you know what it is like to wait in line for something or another. You are more likely to be able to adapt to changes more often than not as larger families are used to adapting more things.
A few more things that help mold you and give you more character might also include what type of ethnicity your family was. The larger more family oriented Italian, Greek or even Mexican nationalities, might have taught you that being surrounded by family will show how to make a holiday a real holiday, or other smaller more intimate family gatherings might show you that is what holidays should be like.
If you are one of many in a family then you know what it is to achieve a goal and you know what it is to be out shined or under appreciated. Where as a single child has the sole attention of your parents so they might always feel like a star and never know what it is like to be out shined or not feel as important.
If you come from a small family you parents might be more likely to help to afford college and get into a better college, and a larger family might not be able to afford to send all the children to college, so they might not be able to get as educated.
These are just a few examples of what your place in a family might play on you later in life.