Long-term unity and stability in a complementary sex role arrangement is essential in human development since humans take the longest to develop of any species, approximately 21 years. We are not mere machines or robots that can be arbitrarily sculpted to fit ulterior motives without dire consequences, but instead biological creatures linked to what best maintains and perpetuates life.
If we are talking about the "traditional family values" of loving and respecting one's family members, then they are important for child development. However, if by "traditional family values" we are talking about traditional heterosexual couples and all that, then I don't think those are nearly as important. I personally think that a couple consisting of a man and a woman is slightly better for a child than a homosexual couple, but I also don't believe gay adoption should in any way be blocked, as a happy home will always be better than a broken family. That is the real "traditional family value," raising a child in a happy and supportive environment.
Values are really important to any child development. It does not matter if they are traditional or not. I feel that traditional are the best for me and my family. It may not be what is the best for all kids though. As long as kids have a stable environment and something to believe in that is what is important.
Every family is different and what makes them different is there culture. And even in every culture there is people who are different, they are set apart by there family values. If all family values were to be trashed and forgotten then every family and every culture will be the same and individuality will be gone from this world. People dress, eat, live, behave, talk , and many more things people do emerge from family values. If they were gone every person would be the same and if a child is not taught when young then they will never learn. If family values are not taught when young then there value may not be understood when they are older.
Children need to be given the choice of establishing their own values as innovative individuals. Listening to all opinions and values and raising your children in a multi opinionated environment is essential for child development. Instead of carrying on your own values onto your child you should teach them to think for themselves. Obviously you want them involved in your culture, but have them experience foreign cultures as well.
Traditional family values are not really important, general values are also acceptable. If a family chooses to insert the traditional value style into their household then that is fine, but there are other values that can be instilled in order to maintain order and respect within a household and in your children.
I think people tend to mix up the term "values" and "tradition". They can be somewhat similar, but values are a more broad concept that helps people determine the way they should live their lives. Traditions are events or actions done in remembrance of past memories and as tributes to ancestors or events. As long as children grow up WITH set of values, it doesn't really matter whether they are seen as traditional or not, provided that they foster proper growth and development of that individual.