I think anybody could adopt a child or children, whether you are in a heterosexual, homosexual, or bisexual relationship. 

It doesn't matter who is there with you in a relationship. As long as you are in the right frame of mind and attitude. The proper name may be TransFamily. Transitional Family Relations. Society is always in an Evolutionary Transition. The important point is that we are responsible enough to handle a Mature and virtuous family. Transgender is distinct from Trans Gender. A gay and a lesbian, bisexual and homosexual, a "transgender relationship?". The correct category? Would we be promoting Asexual relations?

The First Creations are Asexual Species. These are Spiritual Beings or Immortal Spiritual Beings, IS-BEs, that can Enter at Will to Any Form of Creation. Spirits are Never Born. They Exist for All Eternity. After Trillions of Years, the Terrestrials Decided to Create a Species with Sexual Reproduction, including Homosapients. For the Creations to Continue to Multifly by Itself...