http://en.wikipedia.org/wiki/LGBT_parenting#Children.E2.80.99s_outcomesConsensus
The scientific research that has directly compared outcomes for children with gay and lesbian parents with outcomes for children with heterosexual parents has been generally consistent in showing that lesbian and gay parents are as fit and capable as heterosexual parents, and their children are as psychologically healthy and well-adjusted as children reared by heterosexual parents,[3][4][5] despite the reality that considerable legal discrimination and inequity remain significant challenges for these families.[4] Major associations of mental health professionals in the U.S., Canada, and Australia, have not identified credible empirical research that suggests otherwise.[5][6][7][8][9] Literature indicates that parents’ financial, psychological and physical well-being is enhanced by marriage and that children benefit from being raised by two parents within a legally-recognized union.[5][6][22][23]
Since the 1970s, it has become increasingly clear that it is family processes (such as the quality of parenting, the psychosocial well-being of parents, the quality of and satisfaction with relationships within the family, and the level of co-operation and harmony between parents) that contribute to determining children’s well-being and ‘outcomes’, rather than family structures, per se, such as the number, gender, sexuality and co-habitation status of parents.[4][22] Since the end of the 1980s, as a result, it has been well established that children and adolescents can adjust just as well in nontraditional settings as in traditional settings.
I know the above is from Wikipedia, and no doubt those that have contrary views could find articles supporting their beliefs, but the above - especially the part I've bolded - sums up my views better than I could articulate myself.
If it is not right to deny a child the right to know its biological parents - should all adoptions be frowned upon, or only those made by same-sex couples?
There was a time when it was quite normal for daughters to marry whoever their fathers told them to, with little or no importance placed on their preference.
There was a time when it was generally accepted that only a man had the right to own property, and only men could earn money, hold jobs, be members of parliament etc.
There was a time when white people felt they had the right to sell other humans of a different colour as slaves.
There was a time when only men could vote, and many considered the very thought of this changing to be outrageous.
There was a time, not that long ago, that our own Australian aboriginal population were considered good enough to go to war for the country, but not good enough to vote or to be left to raise their own children.
There was a time when inter-racial relationships were considered to be scandalous.
There was a time when equal pay for women for the same job was extremely rare, and women had to resign upon marriage.
I firmly believe that one day our children and grandchildren will look back at this present debate and wonder "how could they think that was right", as I wonder how people in the past ever thought the above "norms" were right or acceptable.
Society evolves. Some wish to cling to the old ways, and they are just as entitled to their beliefs and opinions as anyone else, but in the end the beliefs of the majority will prevail - it's just a matter of time. Personally, I think it is wrong to deny a (growing) section of our community the same rights and privileges that fall to the rest of us.