Why can't it have 2 Dad's, 2 Mum's or just 2 parents?
Are the children loved or wanted any less?
We don't stop people in the LGBTQ community adopting pets based on how they identify, and yes that might be a strange analogy, but people are good parents (and good people) or they're not regardless of sexual/gender orientation.
I don't see the problem?
I agree with this, the gender / sexual orientation of a person should not change their ability to parent a child or pet. The fact that this is even a debatable question is appalling.