First problem solved.<quoted text>
1. There are NO biological children of gay unions to compare. Never has been, never will be. Ever.
2. The only comparison possible is children in biological families or step-families. Children with only one biological parent only qualify for step-family situations.
Of course parenting skills matter. But as the Cinderella Effect points out, biological parents have a distinct evolutionary advantage. This is summarized in the adage, "Blood is thicker than water."
You don't have to be a biological parent, to be a parent. If you feel differntly please don't adopt, or marry someone with children.
Second problem, solved.
It would seem using the cinderella effect, would just come under poor parenting skills.