There is ample evidence to show that children raised by same-gender parents fare as well as those raised by heterosexual parents. 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. The rights, benefits, and protections of civil marriage can further strengthen these families.via The Effects of Marriage, Civil Union, and Domestic Partnership Laws on the Health and Well-being of Children — Pawelski et al. 118 (1): 349 — Pediatrics.
h/t Drew Tatusko.