You forgot - do they exhibit normal male/female relationships. Since homosexuals want to be considered normal as opposed to freaks, allowing children to be adopted would be the same as saying the state recognizes homosexuals as normally functioning human beings. Behavior of the adoptive parents HAS to be part of the criteria.
Normal for homosexuals is achieving orgasms with the same sex, and they would be exhibiting cuddling, fondling, kissing of the same sex in FRONT of the child. This is quite sick. Horrid, actually. ( Normal for serial killers is continuous killing.)