Most people agree that the way your parents treat you as a child affects your personality as an adult. How? 
Two major contributors to this idea are Dr. Ainsworth and Dr. Simpson. Ainsworth conducted a study known as the strange situation test. In this study, a mother and her baby are put in a room in the lab. After a while, the mother leaves the room and the baby will cry. Ainsworth was interested in how the child reacted when his or her mother came back. If the baby had a secure attachment style, they would seek comfort in the mother and be successful in calming down. With an avoidant attachment style, the baby would cry until the mother came back and pretend not to care. They try to self-sooth and are not very successful in calming down. An anxious-ambivalent child wants to he held but also pushes away. They need the comfort from their mother but the baby is mad at her.
How are these behaviors created? If parents drop what they are doing to comfort their crying child and try to help them calm down, they will create a secure attachment baby. If the parents are emotionally rejective and leave the baby to calm down on his or her own, they will create an avoidant baby. Finally if the parents are inconsistent and sometimes comfort the child while other times ignoring the cries, an anxious-ambivalent child will result.
How does this affect our dating lives? Your parents create what type of attachment style you will possess as an adult. However, due to experiences in an individual's life, this style can change. Parents aren't the only factors that form attachment style but I think it is interesting they can have an effect on it. If you exhibit a secure attachment style, you will trust your partner and be able to provide love and support. If you are an avoidant individual, you will be defensive and withdrawn from your romantic partners. If you are anxious-ambivalent, you will tend to smother your partner because you are afraid of abandonment.
As you can see, being in a relationship with a secure individual is the ideal situation. The other two attachment types tend to cause problems and be frustrating. I think this is an interesting study because the way parents treat their babies can have huge effects on how they deal with romantic relationships. Your parents could potentially mess things up for in regards to your love life. Keep in mind other thing that happen in your life can alter your attachment style, your parents can't take all the blame in most situations.
What other things can alter attachment? Where did you get your information (cite/link to sources)?