Argument: Lesbian and gay parents are every bit as fit and capable as heterosexual parents and their children are as psychologically healthy and well-adjusted as children reared by heterosexual parents
"Case No. S147999 in the Supreme Court of the State of California, In re Marriage Cases Judicial Council Coordination Proceeding No. 4365, Application for leave to file brief amici curiae in support of the parties challenging the marriage exclusion, and brief amici curiae of the American Psychological Association, California Psychological Association, American Psychiatric Association, National Association of Social Workers, and National Association of Social Workers, California Chapter in support of the parties challenging the marriage exclusion": "The scientific research that has directly compared outcomes for children with gay and lesbian parents with outcomes for children with heterosexual parents has been remarkably consistent in showing that lesbian and gay parents are every bit as fit and capable as heterosexual parents, and their children are as psychologically healthy and well-adjusted as children reared by heterosexual parents. Amici emphasize that the abilities of gay and lesbian persons as parents and the positive outcomes for their children are not areas where credible scientific researchers disagree. Statements by the leading associations of experts in this area reflect professional consensus that children raised by lesbian or gay parents do not differ in any important respects from those raised by heterosexual parents. No credible empirical research suggests otherwise."
"The Effects of Marriage, Civil Union, and Domestic Partnership Laws on the Health and Well-being of Children" Pediatrics. 2006: "More than 25 years of research have documented that there is no relationship between parents' sexual orientation and any measure of a child's emotional, psychosocial, and behavioral adjustment. These data have demonstrated no risk to children as a result of growing up in a family with 1 or more gay parents. Conscientious and nurturing adults, whether they are men or women, heterosexual or homosexual, can be excellent parents."
Marriage of Same-Sex Couples – 2006 Position Statement Canadian Psychological Association: "A review of the psychological research into the well-being of children raised by same-sex and opposite-sex parents continues to indicate that there are no reliable differences in their mental health or social adjustment and that lesbian mothers and gay fathers are not less fit as parents than are their heterosexual counterparts."
"Legal Recognition of Same-Sex Relationships in the United States : A social science perspective." American Psychologist. 2006: "Despite considerable variation in the quality of their samples, research design, measurement methods, and data analysis techniques, the findings to date have been remarkably consistent. Empirical research to date has consistently failed to find linkages between children’s well-being and the sexual orientation of their parents. If gay, lesbian, or bisexual parents were inherently less capable than otherwise comparable heterosexual parents, their children would evidence problems regardless of the type of sample. This pattern clearly has not been observed. Given the consistent failures in this research literature to disprove the null hypothesis, the burden of empirical proof is on those who argue that the children of sexual minority parents fare worse than the children of heterosexual parents."
"Lesbian, Gay, Bisexual and Transgender (LGBT) Parented Families - A Literature Review prepared for The Australian Psychological Society": "The family studies literature indicates that it is family processes (such as the quality of parenting and relationships within the family) that contribute to determining children’s wellbeing and ‘outcomes’, rather than family structures, per se, such as the number, gender, sexuality and co-habitation status of parents. The research indicates that parenting practices and children’s outcomes in families parented by lesbian and gay parents are likely to be at least as favourable as those in families of heterosexual parents, despite the reality that considerable legal discrimination and inequity remain significant challenges for these families."
"How Does the Gender of Parents Matter?" Journal of Marriage and Family. 2010: "No research supports the widely held conviction that the gender of parents matters for child well-being."
"Affidavit - United States District Court for the District of Massachusetts" Michael Lamb, Ph.D. 2009: "It is well-established that both men and women have the capacity to be good parents, and that having parents of both genders does not enhance adjustment. Based on a significant and well-respected body of research, the scientific community has reached consensus that parental sexual orientation does not affect adjustment. Numerous organizations representing mental health and child welfare professionals have issued statements confirming that same-sex parents are as effective as heterosexual parents in raising well-adjusted children and adolescents and should not face discrimination. See Exhibit B. These organizations include the American Academy of Pediatrics, the American Academy of Child and Adolescent Psychiatry, the American Psychiatric Association, the American Psychological Association, the American Psychoanalytic Association, the National Association of Social Workers, the Child Welfare League of America, and the North American Council on Adoptable Children."