Marry any one of them

One day a young girl and her friend said to his father wants to marry. After using him for a while, he said to his daughter that she can not do because it's half-brother. The same problem arises even more than four times! The girl begins to happier. He goes to his mother and said, "Mom ... What you've done your whole life? Dad since almost every girl, with the city and now I can not marry or five other guys that I like, because they already on my half brothers! "
His mother replied: "Do not worry, my love, you can marry one of them would like, it's not really your father."