I dont think it is bad. Because at least you and your family know her, and her parents, and how she was raised, etc. Its not like your getting someone that has a hidden past and will give you a surprise later on in the marraige.
These type of marriages are not bad. I know the new society that emerged in the world (western) sees this as odd, however, almost all the people that are in charge of countries today come from this specific type of marriage.
Here is an interesting thing I will leave you with, this type of marriage is the only marriage that has the potential to unlock a special gene data type that results in a superior child being born. It has been known through animal breeding and studies. Take 2 rabbits with different blood and breed them, the baby will come out normal. Take 2 rabbits that are cousins and breed them, and one of the offspring will come out with a superior genetic makeup. One rabbit born of a brown colored mom and a black and white colored male, came out with fur that looked gold colored in the sun, and was highly intelligent and very pretty.