A new study called the Australian Study of Child Health in Same Sex Families (ACHESS), the largest of its kind, has confirmed what years of research on same-sex parenting has been finding: children of same-sex couples are just the same as children with heterosexual parents, and in fact possibly healthier and happier than their counterparts. 315 same-sex attracted parents in Australia completed surveys asking about their family's cohesion, as well as the social adjustment, mental health, and general physical health of their 500 children. Comparing the survey results to a larger dataset representative of the entire Australian population, the researchers found that the children of gay and lesbian couples in the current study scored higher.
The study's lead researcher, Dr. Simon Crouch from the University of Melbourne, attributed the higher scores on family cohesion, or how well the families get along with each other, to less pressure for the parents to adhere to traditional gender roles. He told the Australian Broadcasting Corporation (ABC):
Previous research has suggested that parenting roles and work roles, and home roles within same-sex parenting families are more equitably distributed when compared to heterosexual families. So what this means is that people take on roles that are suited to their skill sets rather than falling into those gender stereotypes, which is mum staying home and looking after the kids and dad going out to earn money. What this leads to is a more harmonious family unit and therefore feeding on to better health and wellbeing.
However, the study did find that the families with same-sex parents perceived more stigma, or more discrimination and prejudice directed at them. Dr. Crouch explained, "for these families it might be something as simple as a letter coming home from school addressed to Mr and Mrs, which wouldn't be appropriate for these families, but it can be more overt and damaging such as bullying in the playground."
According to the results, the more stigma the children perceive, the worse their outcomes. In other words, being raised by two moms or two dads does not itself harm children; it is the discrimination and prejudice these children face from others which may affect their healthy development. Rodney Chiang-Cruise, a parent raising three sons with his same-sex partner, told ABC, "we just have to work a little bit harder to make our kids more resilient." 
The study aims to improve the public's awareness of the effects of stigma, and inform health policy to improve children's outcomes. The results of the study can also strengthen the case for marriage equality and custody disputes, showing that same-sex parents raise happier and healthier children.