In fairness, this kind of thing has only existed for a few years. There has been no time for any studies to be done. The "evidence" will come when we see what these kids end up like as adults.
Adams, J and R. Light 2015 Scientific consensus, the law and same sex parenting outcomes.
Allen, M and Burrell, N 2008 Comparing the Impact of Homosexual and Heterosexual Parents on Children
Anderson, N et al 2002 Outcomes for children with lesbian or gay parents.
Baiocco, R. 2015 Lesbian Mother Families and Gay Father Families in Italy: Family Functioning, Dyadic Satisfaction, and Child Well-Being.
Baily, J 2005 Sexual orientation of adult sons of gay fathers.
Biblara, T. and J. Stacey 2010 How does the gender of parents matter?
Bos, H 2012 Planned Gay Father Families in Kinship Arrangements
Bos, H 2016 Same-Sex and Different-Sex Parent Households and Child Health Outcomes: Findings from the National Survey of Children's Health
I can list over 100 more if you like.